Weather Conditions www.hvdn.org | Dedicated to the relevancy & growth of electronics, maker & amateur radio hobbyists in the Hudson Valley

Friday, November 09, 2018

Event: Poughkeepsie Mini Maker Faire 2018


November 18th 2018 is the Poughkeepsie Mini Maker Faire right here in the Hudson Valley!


The educational event for all ages runs from 10:00 AM to 4:00 PM and is located at the Poughkeepsie Day School located at 260 Boardman Road Poughkeepsie, NY 12603


 There will be many presentations and vendors demonstrating:



Basic electronic soldering



Radio Communications 

Tickets can be purchased in advance through Eventbrite

Wednesday, November 07, 2018

Review: Alinco DJ-MD5T Series DMR Radio

This is the third official article on HVDN about the new Alinco DJ-MD5T series dual band DMR/analog handheld radio, but is the first actual review of this interesting communications tool.

Alinco DMR dual band radio MD-5TGP HVDN
The Alinco DJ-MD5TGP  was released
for sale in the United States in November 2018


Responsibility: Users & Vendors

DMR started life as an open standard digital voice mode for commercial use in 2005 and started to see early amateur radio adoption in 2009 through surplus commercial equipment.

Since 2012, use of DMR in amateur radio has been increasing quickly and starting in 2016 really took off compared to other standards in use by the amateur radio community.


how many DMR repeaters are there?

Adoption of DMR has been largely attributed to low priced Chinese origin radios since DMR is an open standard and expensive intellectual property licenses were not needed, like the offerings from other vendors.
Amateur radio communities around the world generally like to expand the capability of existing equipment and radios such as the TYT MD-380 proved an interesting platform for experimentation.
While DMR equipment to date has offered features more appropriate to commercial users such as wide frequency coverage, amateur radio operators have generally been responsible to only use this equipment within amateur radio spectrum.

IMPACT: Recently in the United States, federal trade restrictions have impacted the ability for certain vendors to sell product legally due to source of geographic origin and frequency capability.

While no one country or vendor is to blame, global demand has created a great opportunity for a responsible vendor looking to sell DMR equipment to the amateur radio community.

Overview:  Alinco DJ-MD5T Series

The DJ-MD5T series radios now offered by Alinco is actually its second DMR offering marketed to the amateur radio community.  Model DJ-MD40 was released as a UHF only option in 2015 but saw little adoption because it was priced much higher than the popular TYT MD-380 or Connect System CS-750.

Alinco is now the first well known Japanese amateur radio vendor to offer a dual band DMR radio with the DJ-MD5 series.

Key Detail: There are two versions of the DJ-MD5.  DJ-MD5TGP includes a built in GPS and the DJ-MD5T does not include GPS capability.

For a price difference of less than $30, the GPS version may be the better option for most users to purchase for future resale value and application expansion. Do yourself a favor and do not cheap out.

Alinco MD-5 Series: Key Specifications 
  • Configurable VHF/UHF Band Coverage
  • Analog FM & Digital DMR Tier I and II
  • Four RF Output Levels (5/2.5/1/0.2 W)
  • 4,000 Channels (Configurable between 250 Zones of up to 250 channels each)
  • 10,000 Talk Groups
  • 160,000 Digital Contacts
  • 2.32 (L) x 4.65 (H) x 1.57" (W/T)
Alinco MD-5 Series:  Key Features
  • 1.7" OLED Color Display
  •  VFO/Memory Mode
  • FM Broadcast Reception (87-108)
  • Repeater Offset Storage
  • Path/Distance to Contact Location
  • Text Messaging
  • Auto Power Off
  • Volume Min/Max Settings
Alinco MD-5TGP Review

With the Alinco DJ-MD5TGP now available for official purchase in early November, lets start off with talking about its configurable band coverage as illustrated below.  The model setting is configured through software and is not keypad programmable. This is a first for DMR radios.  Prior to this, only programmed channels can be "transmit disabled". Alinco allows entire areas of spectrum to be disabled for transmit capability.

There are 13 band configurations and option 11 should be what most amateur radio operators should focus on to remain compliant with amateur licensing and to prevent accidental "out of band" transmission.

Alinco CPS DMR
Alinco DJ-MD5TGP programming software allows
one of thirteen profiles to be used depending on country or
operator specific legal preferences

RF Power Output

Users of the various hot spot devices such as those built on MMDVM and Pi-Star combinations or the latest OpenSpot2 may appreciate the 1/4 watt RF output setting as one of the four possible power options.

Major Benefit: Alinco DJ-MD5 battery life is greatly extended by using low power as to be expected with a hotspot.

Memory Configuration

There is ample storage for DMR specific information and is easy to understand compared to some other DMR radios and appropriate programming software. Common terms:
Digital Contact(s):  Sometimes referred to as the "User Database", this is where up to 160,000 user details with DMR ID, call-sign, name and location are entered.  
Loading the entire database of just parts of it help identify who is speaking just like a caller ID function on telephones.  
A great tool for gaining access to the DMR user database can be found at http://amateurradio.digital/
Talk Groups:  A separate area for the storage of up to 10,000 talk groups allows all the "official 1,170+ Brandmeister talk groups to be stored. 
It is possible to also store the same talk group number with different names to accommodate locally numbers talk groups that are not accessible over networks like Brandmeister, NEDECN, Phoenix, etc 
Channels:   Storage of frequency, repeater shift, analog/digital mode, time slot, talk group, channel name, color code, encode/decode tones, power setting, scan lists, group lists and more are done on a per channel basis.  4,000 channels can be created and stored.
Zones:  Multiple channels can be organized into a zone of up to 250 channels. 
Common examples would be for channels for a specific repeater with different talk groups,  simplex channels and local non-amateur communications such as first responder, rail, and marine communications.  Scan lists can be created much like how a scanning radio such as those made by Uniden and Whistler to not miss communications.
Display Feedback

The color display is easily readable in most lighting conditions and shows all important information.  Navigation for settings shown is done through two soft buttons under the display labeled in green and red.  An up and down arrow key performs further navigation functions along.

DMR display Alinco dual band
Vibrant display as found on the new Alinco DMR handheld radio

The keypad can be used to send DTMF tones or access different functions found in the menu.   Shortcuts or "hotkeys" can also be created to access frequently used functions.

Entry of most parameters of this FCC type accepted radio can be performed by the keypad, including a memory or VFO mode that allows the user to change frequencies to allow for monitoring and tactical changes easily.

The speaker is of a ported design and is above and below the keypad. The microphone is below the green button and above the "1" button. A menu in the radio and software can increase/decrease gain based on user preference.


There is no major need for an instruction manual for this radio as much of the configuration should be enabled in the included software which is easy to follow and understand.
Help and description menus are part of the software to help better understand certain functions. 
Here are few of the more interesting and fun features I think makes this radio a good option for beginner or experienced users.

Alinco MD-5 Series Advanced & Fun Features

A good amateur  radio should be easy to use for access to  information and communication and the Alinco MD-5 is no exception.

Reception in the United States of the National Weather Broadcast system found between 162-163 MHz is possible with the MD-5 and also the FM broadcast band from 87-108 MHz for music, news and more.

Cool Feature: The built in GPS will show location coordinates of the user and also the distance and direction to another DMR user. This function works "radio to radio" and also via Brandmeister based on either the self entered coordinates of a users hotspot or actual location.

A general complaint with many DMR radios with GPS has been no clear way to use it. The Alinco is the first radio aside from the Anytone D868 that has made attempts at this in order to compete with some of the benefits of APRS enabled radios.

Non-Voice Communication

The Alinco DJ-MD5 allows the user to send manually created or preprogrammed text messages while in DMR mode.  This is partially dependent on how each user programs each radio, but it is possible to have voice and text at the same time on the same frequency because of the TDMA based DMR mode time slot functionality.
Cool: How to send text and location data over DMR with TYT MD-380
Text messaging does not work over analog FM, so please consider this when considering the purchase of this or other DMR radios.  Text messaging is part of the ETSI standard that DMR is based on. There is no such standard for analog communications unless one is talking about AX.25 based APRS.

Other Functions

One of the best features of any radio is the ability for it to turn off after a period of in-activity.  Alinco offers this along with a power save function to cycle the receiver on and off to save battery.


The volume setting is unique with Alinco in that the user can create listener profiles to have maximum or minimum volume levels set to avoid ear damage or even by accidentally turning the volume all the way off and missing a potential call.

Alinco DJ-MD5TGP features
The Alinco DJ-MD5T offers interesting features like , but does not
include a "mosquito repellant" function as found on older analog Alinco radios
such as the DJ-195, SJ-S446 and others.


Every few years Alinco offers a radio with some rather interesting features, such as a "mosquito repellent" or "theft protection" feature like "digital monitor".

The MD-5 offers a menu called digital fun that has something very interesting called digital monitor.

Alinco hudson valley digital network programming

This function lets the user in DMR mode allow either one or both time slots to be monitored at the same time.  A function like this can be helpful if the user does not know what time slot certain communications is supposed to take place on

A built in voice recorder allows both digital and analog voice recording for up to 14 hours. Other DMR radios only offer recording on DMR mode.  The Alinco not only allows received audio, but also what is spoken into the microphone.

Super Nice Feature: This may be interesting for those interested in satellite operation and recording of contacts for later playback

As illustrated, there is a lot of functionality this radio is capable of and should become pretty popular.

Any secrets?

The Anytone D868/D878 and BTECH 6X2 are very similar to the Alinco MD-5. Many of the software functions and operation of the radio are roughly about the same.

This will be the topic of a tear down of the MD-5 in the coming weeks, so please look for that on the HVDN Notebook by making use of the tag cloud feature for any content that covers the Alinco MD-5

Overall Verdict


  • Build quality is excellent and the keypad numbering does not seem like it will wear off easily. 
  • Audio quality for signal reception is pretty good and does not seem to struggle at maximum volume.
  • Owners of other DMR radios should be able to learn the Alinco function set pretty easily
  • Code plugs from other manufacturers will either partially or completely work with the Alinco MD-5
  • Battery life is excellent and audio accessories are plentiful 
There will be much more to say about the Alinco MD-5 for sure and it will be interesting if Icom, Yaesu and Kenwood come out with something to compete with Alinco.

Thanks for reading. Ask some questions and share your own comments, if you dare.  

Sunday, November 04, 2018

HVDN [reset] = Is the "Feather" better?

Embedded computing and open hardware in the form of Raspberry Pi, Arduino and a few others have propelled creativity in the maker, electronics hobbyist, STEM education and amateur radio communities in recent years.

A new format standard called Feather has recently come to market and is very exciting, so lets find out why.

Embedded computing you say?

Since 2012, there have been over 19 million Raspberry Pi sold when combining all the different (and improved) versions sold over the years.

Perhaps the biggest competitor to the Raspberry Pi has been the genuine Arduino family of micro-controller boards with an estimated few million shipped.

Both "embedded computing" ecosystems have spawned various forked versions that illustrate the success these two standards have demonstrated both for hardware and software compatibility.

HVDN [reset] is a sub-series of content that compares  different enabling or disruptive innovations relevant to the  maker, electronics hobbyist and amateur radio community.
HVDN [reset] is a sub-series of content that compares
different enabling or disruptive innovations relevant to the
maker, electronics hobbyist and amateur radio community.

One reason that has made both devices popular for add-on device or "hat" accessory development has been standard sizes and pin or GPIO configurations.

This has helped developers create exciting applications quickly & reliably

A new standard called "Feather" has arrived recently and promoted by Adafruit and Sparkfun, both known for providing a range of original add-on products to build even better Raspberry Pi and Arduino based projects.

18 different Feather based products using standard sizing and connections

The [reset] moment

Thanks to Limor Fried and her team at Adafruit along with a number of different vendors like Particle, the new Feather and related terms such as "Feather Board" and "Feather Wing" are poised for a lot of success.

This HVDN [reset] article will explore the "Feather" open hardware ecosystem in  comparison to Raspberry Pi and how it simplified development of our latest project by standardizing on this new small form factor wireless enabled embedded computing standard.

Different sizes of Pi for all appetites

Let's look at how the size of the most well known and current Raspberry Pi offerings look next to each other.


Pictured from top left clockwise are the Pi Compute 3 Module,
Raspberry Pi 3 and Raspberry Pi W Zero



Raspberry Pi has been chosen by HVDN to compare against the Feather format because they all offer wireless connectivity.

Arduino has too many variants to compare that have a similar size to Feather but do not offer wireless connectivity. ESP32 and ESP8266 boards have too many versions.

A major benefit with many of the smaller Feather based products
compared to the slightly larger Raspberry Pi Zero is built
in battery charging, power options and connectivity options.

Arduino versions such as the Nano, Micro, and Lilypad along with the Adafruit Trinket are left out of this review since they lack wireless connectivity.

Plucking Feathers

Specifications help drive standards and adoption, so Adafruit has everything documented on its website to make development easy for most everyone.

Standard dimensions of the Feather help
create easy product development and compatibility
Key Feather Physical Dimensions:
  • The 'classic' Feather and Wing size is 0.9" x 2.0" with 0.1" holes at each corner.   
  • There is one 16-pin breakout strip on the bottom side, centered 1.0" from the left edge.  
  • There is one 12-pin breakout strip on the top side, 1.2" from the left side.  
  • The spacing between the two strips is 0.8"  
  • Don't change the GPIO spacing or location, or you will not maintain compatibility with Wings! 
Key Feather "In/Out" Specifications

Using the Particle.IO "Argon" product as the example, here are the connection details copied from the super helpful datasheet.  Many of the elements found in certain Particle products were even part of the attendee badge at this years Open Hardware Summit to show example of an embedded application in the real world.




So, what is the project?

In 2017  HVDN started to develop a modern field strength meter that has remote sense and analytic capability as featured in the Field Strength Meter Monday series.

After working out the actual sensor part of the project and offering for sale a limited run of stand-alone sensors, we then set to work to redesign the RF signal strength sensor unit to fit as a "hat" onto a popular embedded computing board.

The initial plan was to use the Arduino Nano because it was low cost and easy to program but was soon abandoned because certain versions of it used non-standard USB drivers to update or interface to the device.

A later version looked at standardizing around the STM32 based ESP32 and ESP8266 based embedded computing devices because they both offered integrated battery charging and wireless functionality. They also used the very flexible microPython programming language.

WEMOS ESP32 based Wi-Fi/BLE
4MB microPython IoT device
Quality and version control of these different ESP32 or ESP8266 based boards proved hard to develop easily replicated results around, but working prototypes showed the proof of concept was sound and could be improved upon.
Looking at Feather based options again seemed ideal due to a price drop and additional features. 
It was decided to build this project around the Particle Argon (Wi-Fi + Mesh)  and Xenon boards (BLE + Mesh), with potential support for the Boron (LTE + BLE + Mesh) board at a much later date.

Making projects simple with Feather

The Adafruit Feather based options helped simplify our project design and also allowed even more features to be added!

Future articles will cover microPython coding basics, computer-aided circuit design and fun applications for this exciting project.

Here is the HVDN-FS1....

Friday, November 02, 2018

Review: Retevis RT-51 Basic PoC Network Radio

A network radio or PTT Over Cellular (PoC) device changes the way traditional two way radio users think about reliable unlicensed and local/non-local communications.
"Network radios use existing cellular infrastructure just like your smartphone in order to communicate both near and far"
The most basic PoC radio such as the Retevis RT-51 reviewed later in this article has better coverage compared to a smartphone that uses the same network due to antenna placement and configuration.

This creates unique applications and disruptions for those interested in communication equipment not seen since the days of Nextel and its iDEN technology that created the first wide scale PTT/cellular service concept back in the 1990's.

Overview:  Competitive Landscape

To set a baseline comparison, lets first compare competing unlicensed FRS and MURS radio services in the United States along with two non-critical licensed radio services known as GMRS and Amateur Radio.

Our goal with this article and review is to inform non-critical communications users about the benefits of network radio solutions.

Comparing the physical characteristics of one vendors traditional
analog/digital VHF/UHF radio (RT-3) and its basic network radio (PoC) offering (RT-51)

Licensed versus Unlicensed Radio

In the United States, there are specific frequencies that can be used with no license.  Most of these are designed for consumer use and occasional business use of a non-critical nature. 

Family Radio Service (FRS) and Multi Use Radio Service (MURS) offer different benefits to its users looking either for local or mid range communication. 

FRS uses 14 channels in the 462 and 467 MHz range with a maximum power output of  500mW and no ability to use external antennas.  No more than $60 USD for a pair of basic FRS radio often needs to be spent and the most professional quality FRS radios with other features like weather broadcast reception often sell for less than $150/pair. Average realistic communication range is less than 2 miles.

Example FRS radio made by Retevis. FRS in the United States or PMR and other
 similar services in other countries offer clear local unlicensed voice communication

MURS in comparison to FRS has only 5 channels with up to 2 watts of transmitter power and the ability to use external antennas for greater range.  There are some business users who still use these channels that at one point were called "green dot", "blue dot", "red dot", etc itinerant channels before MURS was an official service in the United States less than 10 years ago.

For a dedicated MURS only radio, pricing would be $150 to $400 for a pair of them. Average realistic communication range is about the same as FRS, but will tend work for greater distances in unobstructed residential environments or more reliably outdoors.

A MURS radio tends to be more expensive compared to FRS radios and there are fewer consumer grade options available for purchase which keeps MURS as a "best kept secret" for reliable mid range unlicensed communications.

Motorola offers its model RDM2020 and RDM2025 as
MURS only radios available for consumer purchase

With either the FRS or MURS service, communications is often limited to less than 3-5 miles.  There is no legal way to increase the range of these services with repeaters. General Mobile Radio Service (GMRS) does however offer this capability however for extended communication range.

Important: There are very few "legal" radios that combine both the VHF MURS and UHF FRS/GMRS functions into one radio.  There are many capable radios to do this however.

GMRS is unique as a licensed service that shares a few overlapping channels with FRS for some level of licensed/unlicensed interoperability.

Basic combinations of GMRS and FRS radios can usually be purchased for less than $100/pair and the advanced repeater capable radios selling for not much more.

Standard FRS radios are advertised as 14 channel models and the FRS/GMRS versions are 22 channel, not including the input frequencies for repeater GMRS operation.


Business users such as property management companies, construction, maintenance and other non-critical communication users have little choice but to turn to specifically licensed frequencies should they require greater coverage range or privacy. 

Pricing for licensing varies along with equipment maintenance and compliance costs. A general overview of licensing costs can be found here.
GMRS is typically not the best for business use because other unlicensed users may interfere with important business communications.
Citizens Band (CB) at 27MHz is mentioned only in passing within this overview of unlicensed radio services due to different characteristics too dissimilar in operation and equipment compared to FRS, MURS, GMRS and amateur radio.

Amateur radio is a licensed non-commercial communications tool that offers the benefit of all the characteristic benefits of different frequencies and spectrum plus the ability for larger antennas and higher power.
A basic amateur license in the United States is known as the Technician Class and permits the use on any frequency for any type of communication above 28.3 MHz and limited data only communication below. 
Gaining a license to become an amateur radio operator is very easy and there are very affordable radios that can be used on part or all of the most common spectrum in use with its 700,000 users in the United States.


Selection of modern amateur radios that offer different combinations of spectrum and communication modes.
MSRP range from $150 to $500 for those pictured.

Amateur radio also offers true "radio to radio" capability, communication through repeaters for extended range when using inexpensive hand held radios and also decentralized networks such as Brandmeister for a mix of local and global communication capability, like that offered by a  network radio.

This is without mentioning long range HF 1.8 to 30 MHz communication which most people associate with amateur radio which often leaves out the VHF and UHF offerings including 144-148 MHz, 220-225 MHz, 420-450 MHz and even 1.2 GHz!

Here is a comparison chart between the different services and spectrum the services covered in the article can be found.


Retevis RT-51 Network Radio Review

The Retevis RT-51 is very well built and feels like its capable to stand up to daily use in bad weather.

The manufacturer lists its IP67 rating for moisture and dust resistance as part of its features which also include loud volume, easy to push buttons and a simple menu system to access key features.

A full color display shows the incoming caller name to help identify who is speaking.  Time, date, battery life and network signal strength also appear and is easy to read in most lighting conditions.

The RT-51 can also announce various operational parameters for the visually impaired in situations where looking at the display is not possible.

The Retevis RT-51 and the TYT IP-350 are identical radios.
The major difference with Retevis is more responsive
customer service and possibly warranty support.

Operation of the radio is very easy with a power and volume function built in to one of the top mount controls.
The knob between the volume and antenna allows the user to select between different groups, explained later in this review.
At a price of less than $150 each, the Retevis RT-51 is unique in that it is a high quality product for a moderate price similar to that of its line of equipment marketed towards amateur and commercial radio users, such as its VHF and UHF only radios along with dual band versions.

Retevis offers the least expensive and basic network radio (PoC). 
Competing and more complex network radios  can cost more than $500 each.

Many manufacturers today offer digital communication capability such as DMR which has been adopted as the replacement for aging analog only radios. Benefits of DMR include user identification, location tracking, flexible group or private calling and management of users through special programming and console software.

RT-51 Experience: Out Of The Box

It is not possible to buy one, two, five or one hundred  of these radios and use them without first having two critical items.

Critical Item #1:   Each radio requires an inexpensive cellular prepaid or post paid data plan that will work on compatible mobile networks such as AT&T and T-Mobile.

A SIM card will need to be installed in each radio so it can work. No "radio to radio" calling feature is possible without a network based data plan with the Retevis RT-51. The spectrum that the Retevis uses is licensed to the mobile carrier networks such as those found at 800 and 900 MHz plus  1.7 GHz, 1.8 GHz 2.1 GHz and 2.6 GHz. There is no 2.4 GHz Wi-Fi of 2.3 GHz amateur spectrum accessible in the RT-51's ZTE 3630 4G LTE modem

The great news is that even with the least expensive $7.99/month plan on offer from FreedomPOP which offers 2 GB per month, the radio will likely only use 25% of that bandwidth even with heavy use. For users looking for many radios, it could be possible to pay even less per month per radio on a data plan.

No matter where a user is the radio will work just as long as there is network coverage available. This translates to 95% or better percent reliability in most any area that network operators cover.  This is a major benefit of a network radio compared to traditional radio. Plus, there is no need to invest in infrastructure, such as a repeater.

Underside of RT-51 showing the
removable door and SIM card slot

Critical Item #2
:

Once the radio has a data plan and SIM card - the radio needs to communicate to a server that routes communication between users.



Retevis offers two different options to make operation of the RT-51 easy.  For $10 a year, Retevis can host the PTT Smart Dispatch software on a US based server.

All that needs to be done is share the user ID for each user with Retevis and let them know how to set up groups for your users.

Easy menu navigation allows selection of
Group, Member, Friend, Recording, GPS, Setup

Each user can contact each other by "private call" or all users assigned to specific groups.  This "hands off" option is best for users who do not need to track user locations from a central dashboard.
  • Group:  Allows a user to contact any member that is assigned to the listed group
  • Member:  Real time list of online users are shown and user can contact other members through a private call
  • Friend:  Server and Local "Friends" can be selected to contact that are managed through the PTT Smart Dispatch software. 
  • Records:  Shows a listing of incoming and outgoing calls specific to the users radio.  Playback of missed calls is possible.
  • GPS:  Will show the location coordinates of the users radio based on GPS satellite reception.
  • Setup:  Provides control of PTT sound, back-light control, audio guide and a few other functions
A second option allows Retevis to sell a license to the Smart PTT Dispatch software for the user to install on a server they currently have.  This option lets the user manage all radios, group settings and view real time maps for all radios.  Pricing is negotiated with Retevis on this option directly.


While this may sound complicated, this approach creates a lot of very interesting capability, including the ability to manage radios on a private LTE networks which are growing in popularity in fields such as mining, agriculture and others.

Feedback on the RT-51

This may sound sort of funny, but Retevis should have included Wi-Fi in this product or at-least offered another version that included it. 

Had Wi-Fi been included, it would have allowed users an option for limited range "radio to radio" communication or to use the radio without the Smart PTT Dispatch software.  It would have also offered an option for brand loyalty and later upgrade capability dependent on user requirements such as in places where there is not good mobile network coverage, but good in building Wi-Fi connection.
Other "Network Radios" offer Wi-Fi  or even low power UHF as standard, so why not Retevis? 
There are reasons that the battery is slightly different than those in use by its popular VHF/UHF radios both in physical dimension and voltage, but it may have created more brand loyalty and interoperability to have used the same battery.



From a hardware perspective, there is not much else that should have been changed to keep this product at a moderate price point. Headset accessories are plentiful and uses the common Kenwood 2-pin configuration.

Key Comments

  • Battery life is excellent and only has shorter use time based on the GPS being on all the time, but can be shut off.  5 days with the radio powered on in standby mode was great and about 2 days with moderate use was common even with GPS on.
  • Direct competition for Retevis will likely come from Inrico and Peak PTT, but Retevis comes out ahead on price point.
  • Both competitors seem to have a more mature approach towards the software and dispatch management that are required for all network radios to work.

While a negative comment against Retevis, they may be able to innovate by investing in the Smart PTT Management Platform software development. 

In comparison,  Inrico has done well by integrating with the Zello and IRN PTT applications that are well known for providing "walkie talkie" like functionality on smartphones.

Peak PTT may be lesser known and will likely be the closest competitor to Retevis. The United States based competitor seems to offer better radio management software and features, but are more expensive than the RT-51.

RT-51 Final Verdict - Wearing Different Hats


  • The "Pretend Local Small Business Owner Hat" - The RT-51 is interesting for a business looking for reliable communication and not interested in maintaining any equipment aside from paying a monthly bill.  
  • The "Pretend Larger Business User Hat" - The RT-51 with its location tracking capability and ability to host the Smart PTT Platform locally will give control to the business owner with minimal infrastructure to maintain, especially if they already operate a computer server for other business functions.
  • The "Amateur Radio" Hat - The RT-51 will not be of interest to the amateur radio community without taking the radio apart to make it do something it is not intended for.
  • The "Communication Hacker" Hat - The RT-51 may be very interesting since this radio is nothing more than a cellular modem with various I/O capability. 
  • The "Concerned Family/Church Leader" Hat - The RT-51 monthly fee may be hard to handle, but a prepay data plan could be great peace of mind for for this solution over other unlicensed services when it is needed.  Group trips, community support and other non-commercial activity are great application examples for the RT-51.
  • The "Business Strategist Perspective Provider" Hat - The RT-51 is a great piece of hardware but will likely not do well from a sales perspective unless distributors and integration specialists are made aware of it.  The lack of polished software management and lack of known APIs will also prevent serious interest in this product since many will want full control of the hosted Smart PTT Platform rather than having it run somewhere unknown "in the cloud" since it can impact user privacy due to the embedded GPS capability. 
In Closing....

As an unlicensed communication tool, the RT-51 is a great idea, however paying a monthly fee to a mobile operator along with a very low annual server host or dedicated software license purchase outright that is hard to get clear pricing from the vendor, may create more business for the competition. 

Friendly Suggestion

Retevis has a great opportunity but really needs to look at where the real revenue and value is to its users as part of its sales and marketing strategy.

Biography on the author

Steve Bossert currently works for a Hong Kong based research & technology advisory firm. His role is to manage and grow the business visibility in North America for the unique capabilities of his company. Prior to this opportunity, he has worked for other well known strategic consultant firms over the past 15 years.  His expertise includes strategy for multinational semiconductor, mobile wireless, infrastructure and diverse emerging technology companies. 

Before graduating university and while in high school, Steve became a licensed amateur radio operator. Steve has the ability to blend his natural technology curiosity and business acumen to provide unique perspectives for both his professional and hobby interests.  Steve currently resides in New York with his wife Jennifer.






Sunday, October 28, 2018

SSTV: Images from the ISS

Zipping around planet Earth at 220 miles above on October 27th to 29th 2018 was the International Space Station and its special series of image transmissions using amateur radio slow scan television (SSTV)


What is SSTV?

Slow Scan Television or SSTV for short is a method of sending images over very narrow wireless bandwidth with fairly good color resolution in a short amount of time.

There are many different types of SSTV signals or modes and the one currently in use by the International Space Station is known as Robot36 or PD120

145.800 MHz is the "down-link" frequency for amateur radio operation from the ISS.  Sometimes it is used for voice communication and other times it is used for experiments such as SSTV.   On 145.825 MHz is data "packet" APRS operation for two way "text message" like contact with or through the ISS>

How To Receive SSTV Images?

There are two inexpensive ways to receive and decode an ISS SSTV transmission that can be done with less than $50 of equipment, not including the cost of your computer or smartphone.

Method #1:  USB SDR Dongle & Computer Setup 
Wide band software defined radio (SDR) receivers such as the RTL-SDR v3 can be used for many things, including the reception of signals orbiting above you and around you.  
Other things you can use this 24 MHz to 1.7 GHz  "SDR" receiver for include finding your lost car key remote, monitoring smart home devices, listening to weather, music and so much more.
With free software such as SDR#, its possible to record a "visualization" of the signal for later playback and decoding of SSTV signals. The same signal can also be sent from SDR# to MMSSTV software in real time for decoding of the SSTV transmission.



Method #2:  Inexpensive VHF/UHF Hand Held Radio & Smartphone Setup 
A basic dual band hand held radio can be purchased for about the same price or less as the receive only SDR but will also offer the ability to transmit on a narrow range of amateur frequencies also used by the ISS as well as by over 2,500,000 amateur radio operators globally. 
A very simple way of decoding a SSTV transmission is to simply hold the radio next to your smartphone while running the Robot36 application found on in your favorite mobile app store. By turning the radio volume up, the microphone on your smartphone will hear the SSTV signal and decode it. Sample signals to listen to are found later in this article.
The application will decode the received audio with no physical connection to the radio which makes this very easy to demonstrate for those not very computer savvy.  

Antenna Stuff:   Very important!

While any combination of radio receiver and computing device can be used beyond the examples provided, antennas are just as critical if not more so for receiving the best signal possible.

Having what is called a good "Signal To Noise Ratio" or SNR is needed to help differentiate white noise and static from the actual SSTV signal.  Any interference to the SSTV signal will just look like static like on a television screen, so a good antenna helps increase the SNR and produce a better picture

The good new is that the ISS SSTV signal is often very strong and easy to pick up with basic antennas, but a high power directive antenna is a good idea for optimal reception since it will focus the maximum signal strength from the ISS into your radio.

The reverse polarity SMA-J connector is common on Chinese origin radios such
as those for sale by Baofeng, Wouxon and a few others. 


While good reception results will often be had with the including telescoping dipole antenna with the RTL-SDR V3 or the longer "whip" antenna included with many of the inexpensive hand held analog radios such as the UV-8, a directional antenna is a good idea to consider.

Some options that can be purchased separately made by companies such as Nagoya, Comet and Diamond are easily sourced for VHF only of VHF/UHF operation.

It is best to pay close attention to what type of connector on an antenna like this can be used with your radio as they are not all the same.

The SMA antenna connector version of this same antenna is more common for radios
\made by Alinco, Kenwood, Icom, Yaesu, TYT and Retevis.


An alternate and higher gain antenna called the tape measure yagi beam can be constructed with simple hand tools and materials for less than $20.

There is also a ready made antenna available for purchase from the Arrow Antenna Company as well as the Elk Periodic from vendors such as Ham Radio Outlet.



The beam antenna is a great club project or one for a few like minded hobbyists. Many can be constructed quickly at one time if people work together in cutting and preparing different parts of the antenna for final construction..

What does a SSTV signal sound like and how do I find it? 

In order to know what to listen for, below are three very good signals and the resultant decoded image.

Feel free to try decoding these files with the MMSSTV or Robot36 applications to get familiar with the software since you do not want to miss the fast traveling ISS the next time they are transmitting SSTV images.

The "ISS Detector" app for Android is a great way to find out when the ISS will pass over your location next.
You an also track other satellites and even planets too with this program


To find out when the ISS will be over your location next, please visit AMSAT.org for more information about tracking the ISS, satellites and other interesting space related amateur radio topics.

SSTV space station file
Play MP3 Recording:  10:28AM 10/28/2018 ISS SSTV


slow scan television amateur radio space station
Play MP3 Recording:  10:31 AM 10/28/2018 ISS SSTV

space station contact amsat SSTV ISS
Play MP3 Recording: 12:00 PM 10/28/2018 ISS SSTV

How about SSTV with an SDR?

A nice feature with the SDR# software is you can play back a recording of spectrum at any point in time.

This is also called a base-band IQ file and was discussed in prior articles about receiving voice transmissions from the International Space Station.

This file is a base-band IQ file for the "Atlantis and Mir" SSTV image to help with your own testing.



Select the  IQ file option  in SDR#
and play back the 225 MB recording 

Share your success stories, questions and comments below.  Thanks for reading!



Monday, October 22, 2018

Happy Monday Again!; Ashford School and ISS Make Contact


The front gate to Burger Hill at Drayton Grant Park in Rhinebeck, New York was closed (and locked) at 8:45 AM this morning, so a quick decision to either quickly go home or find an alternate location to record the 9:05AM rescheduled ISS contact with a school in Ashford, CT was needed.

One of the many student questions that Serena Auñón-Chancellor answered included important ion propulsion technology that may one day take Earthlings to Mars. More below including recordings!

Ion propulsion will be important in getting to Mars - Serena KG5TMT

Tracking the ISS


Orbitron software was used to track the International Space Station. Combined with the software defined radio program, SDR#, its possible to keep the frequency locked on to accommodate for slight drift called the "Doppler Effect".  At VHF ((145.800MHz), the Doppler effect is not as pronounced compared to higher frequency, such as at 445 MHz. 

\
Recording location was far from optimal for best line of site on the grounds of CO. in Rhinebeck on such short notice.

The Ashford Band YouTube channel has shared a video of the setup and ultimate discussion with Astronaut Serena Auñón-Chancellor M.D, KG5TMT.

Reception site of K2GOG in NY and KM1Z down-link site for ISS in Connecticut
YouTube link jumps to 41:50 into the 56:00 video where the actual contact between KZ1M and NA1ISS, operated by Serena.



To both see and hear the down-link signal from the International Space Station, HVDN has two files:


The HVDN files are only “one way” because line of sight from the ISS to where the recording took place was too far away from where KZ1M was located.

Here are some past articles for additional reading:




Sunday, October 14, 2018

NEAR-FEST: What is under the tarp?

Since 2006, amateur radio operators, electronics hobbyists and camping enthusiasts have been making the pilgrimage to New England to experience an interesting two day long event known as "NEAR-FEST"


What is under the tarp you ask?  Some interesting electronics with a military
history for sale at the 24th NEAR-FEST in Deerfield, NH on October 12-13th 2018

Held twice annually, every spring and fall at the the Deerfield Fairgrounds has been the home of a unique event called NEAR-FEST.
Part electronic swap meet, educational session, casual gathering, food destination and opportunity to purchase brand new and interesting radio related equipment offers a little of something for everyone in the family.
Over the years, the New England Amateur Radio Festival has attracted those from both far and wide.

The October 2018 edition was no exception with those spotted from Quebec, Ontario, Virginia, Florida, Ohio, Japan, Haiti, Puerto Rico and of course the entirety of the North Eastern United States!
Event attendees can camp on site in a tent, roll up in an RV or camper or stay at any number of area hotels. 
This makes it a very convenient "ham fest" as compared to other amateur radio or even "maker" oriented events.


New England Tech Trek gives another reason to not leave NEAR-FEST too early
if you are not interested in purchasing something which is one of the
top reasons to go to a "fester" like this bi-annual event 

There is no need for every attendee to contend with an early morning drive or risk there getting late out of fear vendors will pack up early.  Once someone is at NEAR-FEST, they are generally there for a while.
Everything from food, ATM machines and restrooms are available to prevent people from leaving 

Helpful NEAR-FEST Tips

It is recommended however, to bring a backpack to hang on to anything acquired at the "fester".  A bottle of water, comfortable shoes, various batteries, rain repellent are recommended to have on hand too.

Need a rain jacket before going to NEAR-FEST?  L.L Bean h
as you covered at its various nearby outlet locations.
Most of these "forgotten" supplies however can be purchased at an L.L Bean Outlet in nearby Concord or Nashua.  This may be especially of interest to those with interests such as QRP kayak portable, SOTA or other converged ham radio/other stuff sort of activities. 
Over the past years, more commercial vendors both at NEAR-FEST and other similar events take credit card payment, so save your cash to support the tail gate community.
Also, if going with friends, agree on what "secret channel" to use and program a few options in advance to your hand held radio of choice.  All of the common "simplex" channels may be in use, but its still good to have those programmed too.

Frequency Suggestions for NEAR-FEST

If you have a DMR radio, the NEDECN has pre-populated code plugs for all area repeaters of interest to NEAR-FEST attendees.

All you need to add are your simplex and "secret" channels along with configuring them in the correct zone, scan list or receive group. Some "amateur radio" suggestions include:
  • Standard FM analog frequencies such as 146.520, 146.535, 146.550, 146.580, 446.000 and 446.500 with no PL tone.
  • Digital voice DMR frequencies such as 145.510, 145.790, 446.075 and 445.925 saved with TG 99, TS1, CC1. 
  • Your own "secret channel" using FM analog, DMR or some other mode like Fusion or D-Star on 433.0125, 433.920, 147.030 or 223.500
Various DMR radios by Anytone, TYT, Vertex, Motorola and a few others can
easily be programmed for NEAR-FEST thanks to NEDECN's informative website


You can also try one of the "unlicensed" channels for FRS and MURS in order to include your not yet licensed amateur radio friends. A great radio for events like this are the Xiaomi Mijia with smart location sharing reviewed in the past on HVDN.



This inexpensive radio not only is a great discussion topic, but also serves dual purpose for both amateur radio and unlicensed operation in one friendly looking design. No internet is needed for this to work, compared to trying to share location with Google Maps or verbally explaining your location over the radio.

Time To Learn & Get Edu-ma-cated... 

An exciting addition to NEAR-FEST recently is the second annual New England Tech Trek or NE(T)².

This mostly hands on educational event engages children as young as 8 years old all the way up to and beyond the age of 80 years old.

For those not familiar with amateur radio and its infinite list of complexities, NE(T)² helps capture some of what amateur radio is all about to prospective "hams", existing hams or those newly licensed thanks to exam sessions also available at NEAR-FEST.
This year, New England Tech Trek showcased a range of well known habits of the amateur radio hobby that have seen modern changes as well as purely new and innovative applications and technologies relevant to any communications focused hobbyist.
NEAR-FEST XXIV Report

Friday October 12th and Saturday October 13th were the planned days for attendees to enjoy the event and rain only impacted part of Saturdays festivities before the event officially came to a close at 3:00 PM Eastern Time.

Inside three buildings were vendors of brand new equipment and small components. Outside and scattered between various food stalls were tail gate and "tent gate" vendors selling everything from surplus "militaria",  antennas, computers, rechargeable batteries, VHF/UHF radios, HF amplifiers, microphones and test equipment.

Some of the commercial vendors or service providers at NEAR-FEST XXIV included:
Not Just "For Sale" Stuff

There also were organizations focused on various parts of amateur radio visibility scattered throughout these rain proof building to help raise awareness of different parts of the amateur radio community that are built upon like minded members.

The Nashua Area Radio Society was just one of the
organizations that made the NE(T)2 event possible at NEAR-FEST XXVI


Was the ARRL there?

Aside from the expected ARRL attendance via a small table, other leadership and influencers were at NEAR-FEST also making a much larger presence known.

One of the non-commercial sellers had a monitor
that said "My wife said to take all reasonable offers" 


Key organizations present included one of the longest operating female oriented amateur radio clubs called YLRL which showcased its bi-monthly newsletter called YL Harmonics.

Niece, KA1ULN  was enthusiastic to engage with those who braved the weather to attend NEAR-FEST XXVI and it was great to meet her in person.

A national women's only amateur radio organization promoting the hobby since 1934


Booths for various geographic focused clubs such as White Mountain Amateur Radio Club, Nashua Area Radio Society, and the New England Digital Emergency Communications Network to name just a few helped make this a great way to decide who else to spend precious "membership" dollars with too.

Many of these organizations use NEAR-FEST as a great way for its membership to see each other in person as well as to raise funds for club activities through the sale of surplus member equipment, spare parts and even member driven projects.

Craig, N1SFT, oversaw some VYL (Very Young Ladies) complete
a small kit that required soldering 

Pictures, please!

The mixed smell of pine needles and grilled pepper & sausage sandwiches permeated the damp fall air across the fair ground which added to the overall great atmosphere by a well run and planned event by those responsible.
Thank you for all your hard work and effort for yet another NEAR-FEST!
Here are some further photos and commentary related to the event.

Most Curious Antenna Award

At the fall NEAR-FEST of 2016, Steve K2GOG (Co-Founder of HVDN) was seen walking around with a high gain 2.4 GHz antenna which attracted a lot of attention.  For the asking price of $5, it was hard to pass that up. This can be found on his QRZ.com profile page

This year, he was on the look out for something else very interesting to add to the antenna collection, but decided to pass on this 900 MHz corner reflector antenna based on its size and price. This could have been easily modified for 440 MHz, 1.2 GHz or maybe even a lawn chair!



Best Convergence Hobby Tailgate Vendor Award

There is much to say about this photo ranging from the precision GPS antenna attached to the roof of the Toyota RAV4 with the license plate of  "Hiker" to the bumper sticker that could relate to the load of vintage test equipment or his other favorite activity that is not ham radio

Hiker Trash:  Certainly, you wont win any feather-lite
pack tips if trying to take any of this gear out on the trail
Most Popular NE(T)² Discussion Topic Award

Anything to do with satellite operation was a big topic of interest inside the NE(T)² as well as outside. The impressive antenna array used for satellite communication demo  that made use of crossed polarization  14 element 435 MHz Yagi, 7 element 145 MHz Yagi and a 20 element 1200 MHz Yagi on a azimuth/elevation rotator. This is one impressive (and expensive) antenna system!

This impressive satellite communications array is capable of receiving
very weak signals as well as for transmitting very high power for
long range line of site communication


On a much more simple and cheaper scale was the Elk Log Periodic antenna found inside the NE(T)² building. T\

This much less expensive but effective antenna can be used to make contact through low earth orbit satellites such as those covered in the popular "Amateur Satellite Basics: Where, When & What to listen for" article from March 2018.

Not to be left out with all the satellite communication focus is a
high altitude balloon presentation at the right of the small crowd.


Digital Mobile Radio Robustness Network Award

The New England Digital Emergency Communications Network connects over 80 different repeater sites over much of the north eastern United States in order to create a very robust communications network.  The KM3T and W1RCF repeaters located on the fun to (mis)pronounce Mount Uncanoonuc  are part of DMR-MARC which is a different network than the popular Brandmeister network.


Both DMR networks are mostly able to talk to one another though due to great interoperability between those responsible for these tremendous contributions to modern amateur radio communities globally.   NEDECN had many radios on display such as the popular Anytone AT-D868UV along with some Motorola equipment for sale by one of NEDECN's members.
NEDECN did a fantastic job or promoting DMR at NEAR-FEST and they even operated a repeater for NEAR-FEST communications.
Reach For The Sky Award

Any time a number of amateur radio enthusiasts gather is the time to see who has the largest antenna on a car.  Here is one example of an HF mobile operator with a 8 foot long vertical antenna on a station wagon. License plates have been blanked out to protect the identity of this super ham-heros!



The Not Just Ham Radio Presentation Award (Tie!)

Computer and Maker enthusiasts were represented by a presentation about what can be done with a Raspberry Pi.



And, for those looking to get out and do something fun with a Raspberry Pi or antenna project can experience hidden transmitter locating or "Fox Hunting".
A very effective directional antenna can be constructed out of PVC pipes, hose clamps and a measuring tape.


The Last Picture Award 

With the weather getting a little more wet on Saturday, even the "hard core" military ham radio crowd started to pack up early.


Mystery Picture Award


Care to take a guess as to what this is? Sound off in the comments...


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