Showing posts with label APRS. Show all posts
Showing posts with label APRS. Show all posts

Thursday, February 1, 2024

30 Days: Weather Balloons from NY Capital Region

 


After thirty full days of monitoring the National Weather Service balloons launched from the capital region of New York State, here are some observations. 

Hopefully this inspires you to become interested in this unique weather monitoring opportunity anywhere in the United States or other parts of the world using inexpensive and easy to set up equipment.


Twice daily and from more than 90 launch sites in the United States, the National Weather Service releases weather balloons to help monitor upper air observations for the first 15 miles of atmosphere. The closest launch site to me comes from the Albany area of New York and currently the exact location is on the grounds of University of  Albany instead of at an official NWS facility.

Even with all the advancements in space or ground based radar or other sensors, a radio sonde balloon still is one of the best ways to monitor a variety of useful measurements.

Setting up a receiver which listens for these weather balloons is relatively easy and inexpensive. Not much additional knowledge is needed and generally the project of setting up a ground receiver will teach a number of other useful things related to some basic RF and computer related skills to anyone interested in STEM related interests.

30 Days:  What Did I Learn?

Different times of the year of course will have different general weather characteristics. Here in New York, December and January are known to be a bit tricky thanks to cold and wet weather which usually includes some gusty conditions too!

From my home in Poughkeepsie shown as the radio tower on the map, I am easily able to receive the Albany area launched balloons once they generally reach around 17,000 feet AGL. 

Signals first are heard by my antenna at an average of 58 miles south of the launch point and the average furthest signals away are closer to 100 miles usually towards the north east.


Looking at the above map, green target symbols are for where the balloon signal was first received and the red target symbol is where the last signal heard by my receiver system.  A explosion icon is where the balloon reached maximum altitude before it burst and started to descend.

Given the distances involved from my home location, a quick retrieval is not very likely by me but the goal is eventually to capture one and send it back to the National Weather Service.

In general, the wind mostly blows west to east. On more than a few occasions, it got so windy, some balloons traveled so quickly and accurate telemetry was not received for too long. 

On average, locations are sent once every 10-15 seconds and more than 3000 positions are captured per flight. Here is an example of January 22nd to 29th 2024 recordings and general statistics.


The blue lines on the map are the flight paths and there is much greater granularity to be observed when plotting the path on Google Earth. Its worth noting that sometimes the GPS on the balloon sometimes sends a false report for a short time to help explain the straight horizontal or vertical lines on the map.


Within the AutoRX application which is what runs on a Raspberry Pi based receiver along with an SDR dongle, its easy to also output in real time to Google Earth to visualize in 3D, such as to see where packets were not received by looking at the lighter colored part of the map when zoomed in. Sometimes wind gusts make the balloon much faster than the reporting transmissions occur.


Here is a converted MKV to GIF video file zooming around from azimuth and elevation angles to show more details in the North East from receiving site, path and location details during the February 1st evening launch from Albany area.


It is interesting to see how the wind blows is sort of the summary of this article.  Data like this is just one of the many inputs used in more complex weather forecasting.  When the time is right and weather nice, it will be fun to retrieve a balloon once its on the ground. 

Details about that can be found on www.sondehub.org and there are also portable receivers easily created from the ESP32 LoRa boards like the Heltec V3 which also runs other projects like Morserino, HASviolet, LoRa APRS and MeshTastic.

Friday, October 28, 2022

7 Year Itch: Global Digital Repeater Growth



With cooler weather here to stay for a while, its time for another global digital repeater roundup brought to you by Steve K2GOG of Hudson Valley Digital Network.

This has been a 7 year in the making project tracking the different digital voice modes currently leading VHF/UHF repeater deployments, according to data from repeaterbook.com


Every May and October, data has been collected from the leading source of the most accurate source for repeater details globally.  While some local options might exist that may be more up to date, ideally that information should be shared with repeaterbook.com to help out lazy travelers or those visiting an area for the first time who would more easily find this website compared to local club or individual websites.

Leaders:  Most Popular Options

By now, its defacto information that both the proprietary Yaesu Fusion and the quasi open standard multivendor DMR options are by far the most popular.   Low cost equipment helps drive the reasons which justify having more repeaters for these modes.

In the last year, there have been no major developments for new mobile or handheld equipment aside from some small refreshes on existing models like the popular Anytone or Alinco DMR radios. Yaesu has only given us the FT-5DR and FTM-200DR which is pretty good considering they are the only company that makes fusion capable radios which can be used on its 3200+ strong network of repeaters.



P25 is a commercial standard and is not marketed directly to amateur radio operators in any off the shelf non-professional grade equipment, but its growth rate is very strong. Based on how long it took for D-Star by Icom to become popular before flattening out, could we see P25 or NXDN become the dominant force in digital modes?   The answer is likely not, but that is where a new mode called M17 will come into play.

More then digital voice:  M17

All the digital modes mentioned all can do some other tricks beyond just voice communications.  Icom D-Star probably has the most advanced options from sharing location, photo, text and more with other users who have Icom equipment or the no longer made Kenwood TH-D74.

Yaesu Fusion really misses the mark to some degree, but most Fusion radios support analog APRS which increases interoperability for certain use cases.  There are a few DMR radios with very basic analog and digital APRS functions.

M17 which is absent for now on the digital repeater list promises us a true open digital standard for voice with some additional tricks up its sleave such as location sharing or text messaging.

The what's next

This would be a complex opinion based discussion, so lets use the airwaves or social media to discuss this fun stuff instead. Doink! 


Thursday, March 17, 2022

FEB 2017 REBOOT: 2022 APRS on the cheap!

 


Time to finally start going back in the time machine to see how things have changed since the early HVDN days.


Feb 7th 2017:  The first HVDN article

Fellow Hudson Valley amateur radio related organization known as the Overlook Mountain Amateur Radio Club (OMARC) used to have a message board that I used to post content to.

Some of those articles were then mirrored to start HVDN, such as the "Mobilinkd TNC2: Bluetooth APRS on the cheap!"  one but the photo links are now broken since they closed down that message board last year and is where those original images were hosted.  Is that you McFly?

Since the time of that article, Rob WX9O has released his TNC3, which basically does the same thing as the earlier TNC2, but the main improvements for $124.95 include:


    • Bluetooth 4.2 support (dual-mode EDR/LE) iOS Compatible
    • 1200 and 9600 baud capability!!
    • USB serial port
    • DCD and TX indicator LEDs
    • More powerful DSP and modem
    • Higher dynamic range ADCs and DACs
    • Buffered inputs and outputs
    • Input amplifier for improved input level matching across a wider range of radios
    • Optimized for packet radio
    • 900mAh rechargeable battery lasts for 2 full days

Now supposing you already have a smartphone,  VHF/UHF radio and the TNC3 plus cable to hook this all together, you have a pretty portable and capable APRS system.  But is there a cheaper way in 2022?  Lets find out!

Its not about being cheap: 2022 APRS on the cheap!

The TNC3 is actually really great, but without a smartphone and its built in GPS and whatever APRS smartphone/tablet application you want to use, you have a few limitations.

The Appalachian Trail Golden Packet (ATGP) is fast approaching on July 16th 2022 and a specialized APRS Appliance is being developed by an amazing team using off the shelf parts and open software to fill a gap left by manufacturers of ready to use APRS equipment.

It would be easy to just use the TNC3 with an appropriate VHF/UHF radio, but that may not be best for some events such as the historic Appalachian Trail Golden Packet event.

Here is a general block diagram of what the APRS Appliance contains:



Direwolf software is run on a Raspberry Pi computing device which provides a software emulated TNC. 

The DINAH interface provides a safe and stable way to connect the Raspberry Pi to a VHF/UHF capable radio which can handle FSK 9600 baud or AFSK 1200 baud data. 

For a fixed location station, this is all that is needed in addition to the appropriate power sources for the Raspberry Pi and VHF/UHF radio plus an antenna for the radio.

If there was a need for this to be taken mobile, including a USB GPS with external antenna would be needed for continual location updates.  

The additional USB Wi-Fi device shown provides a secondary connection to either debug or provide connection to a smart phone or tablet to view or control the device.

A bill of materials for the basics as above, excluding the VHF/UHF radio, power supply system and antenna would cost about $200 or less.

You said cheap APRS!!

Portable APRS that is full featured is actually a hard thing to do still, even almost after 20+ years and this should not be the case.

With the mobile Kenwood TM-D710 radio being hard to purchase new and the hand held radios they also made being discontinued like the TH-D72 and TH-D74, the only off the shelf options for a full self contained APRS device are the less feature rich Anytone AT-D878UVII+Lanch HG-UV98 and a few Yaesu radios such as the FT-5DR, FTM-300DR  and FTM-400.


Trusted on the International Space Station, the Kenwood TM-D710
is considered by many to be the best mobile APRS radio ever made



Needless to say, to do what the APRS Appliance offers is actually not a bad deal, plus the parts may be on hand or you can repurpose them for other projects.

Surplus commercial radios like the Motorola CDM750 or CDM1250 are great for higher power mobile APRS installations when used in conjunction with the APRS appliance.

Stop being cheap!!!

An option to use a $20 interface cable, old smartphone and almost any inexpensive $50 VHF/UHF handheld radio will not be close to the same data capability as what the Mobilinkd TNC3 or an APRS Appliance can offer for true versatility with an appropriate radio, like an Alinco DR-135 or surplus commercial gear by Motorola, Vertex, Kenwood, etc.

The primary reason is that a lower cost radio does not have the same quality of RF switching and front end needed for a reliable APRS system in mission critical or dense signal environments.

A second reason is that using "voice activation" or "VOX" functions found in some radios would not offer the faster switching and turn around time needed to process higher volume packets.  Dropping packets or partial decoding means failure.

Summer 2022:  More planning than just buying sun screen

For the ATGP event on July 16th 2022 and maybe even the Hudson River Radio Relay event on June 11th 2022, it is critical for all participants to use the same or nearly the same equipment for reliable communications.

Now is a great time to start thinking about your capability and to test it in advance with local friends and not during the actual event.



Wednesday, March 9, 2022

Is it a mag loop? Lets find out!


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF

Here is a preliminary review of a recent antenna toy acquisition thanks to some spare Amazon points.

If this antenna proves to be a good option for MF waves instead of EF waves, this is likely going to become a popular product pretty quick. Let's dig in here, shall we?

MF, EF - What is it? A round antenna duck?

Here the antenna is on Amazon and it comes in BNC, SMA and SMA-J variants so it will pretty much work with most radios if you buy the right one.  

The vendor on Amazon does not call this a magnetic loop and I have not taken this antenna apart to see if a hidden capacitor is in that black bubble at the top of the loop but I suspect there is.

For me, I chose the BNC connector antenna version since using it with an adapter like the ones shown in the "Portable RF Connector Emergency Kit" are always on hand.


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF
Where to find this?   Look on Amazon


How does this compare to the original factory antenna?

The radios tested with the HYS antenna pictured include the Alinco DJ-MD5XTG, the Kenwood TH-D74 and the Lanch HG-UV98 all using the original factory antennae.

A second round of testing was done with all three same radios but with the same aftermarket Diamond SRH320A tri-band antenna.

The test scenario was to communicate via a 2m repeater 30 miles away with all three different antenna options and at all available power levels for each radio. 

The results were from an audible report from different users on the repeater without telling them what I was doing over the span of a few hours on different days.

Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF


Results of Test: Non- Scientific you say?


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF


The reason why I chose to use different radios is that different antennas will work differently based on the radio mass offered as the reflective or counterpoise part of the antenna system. What?   Here, look into counterpoise or "Tiger Tail" if you must learn more...

This test allows us to see more uniform tests in a real world environment instead of lab style results.

For each transmission, the radio was held the same way and at the same height.

Signal reports in green were all positive and as good as one could expect to come from an HT 30 miles from a repeater. Yellow reports included comments of fading or weak signal but still audible.  The red reports were scratchy or not very pleasant sounding.

At first pass, we can say that the HYS "Loop" antenna and stock antenna are all pretty much about the same results.  As expected, the longer and higher "gain" Diamond antenna worked the best.

Now with some baseline curiosity under control, lets do something more scientific in terms of radiation patterns and reception tests.

Is this an EM or RF antenna?

To test if the HYS functions in the "electro-magnetic" wave or the "electric" wave function,  I used a field strength meter to check radiation patterns of all three antennae at three distances outside in my backyard away from anything before it snowed this morning.


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF


Based on the test data as expected, stronger signals from the stock and Diamond antenna were strongest when they were vertically oriented which matched the polarity of the sense antenna used with the field strength meter.   

When transmitting with the radio held horizontally, the field strength meter dropped to more than 70% less than what was shown in the vertical test.

Here is the interesting thing with the HYS antenna though. No matter which orientation (horizontal or vertical) the same signal strength was recorded at the field strength meter.

MATH TIME  (1005/146.500 MHz = 6.8 * 12 = 82.3 inches)

Rotating the HYS antenna to have the edge of the hoop or broadside of the hoop aimed in phase with the sense antenna did not show any major differences unless I moved to the furthest test location which was five full wavelengths  away from the sense antenna.  

At the one and three wavelength distance, there was no major difference with all three radios transmitting at highest power levels.

What does that mean?

I think it is safe to say that the polarization of the HYS antenna does not conform to the normal EF wave portions and this seems to function like a true magnetic loop when used for transmitting since its polarity and field strength are very different.

For reception, there is a very sharp null off the edge, but it is very sharp.  Testing this with an attenuator built in to the Kenwood TH-D74 while tuned to the local repeater or NOAA Weather station which are known locations was the only way I could tell there is a sharp null.

Magnetic waves work differently compared to electric waves.  When a true EM or MF antenna is used, signals received may be lower, but with less noise.  This means that the "signal to noise" radio is higher and better for reception usually.   This is what makes a true MF antenna interesting.


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF


This  becomes important especially for HF frequencies where there is more man made noise than ever.  Even still, today more man made noise also happens in the VHF spectrum and this small loop might come in handy. 

If you want to learn about EM antenna, especially for HF, use your Google subscription to discover more about that. Many options exist, including overpriced commercial products and many DIY projects that are fun to look at if you are interested in this for HF spectrum communications.

Further Testing Needed

There are not many people local to me involved in casual non-contest 2m SSB or FT-8 activity to see how well this will work as a portable antenna for SOTA with the Icom IC-705, so that will have to wait.  

Some testing on APRS however has been interesting but will need to drive around with the antenna on the roof for more testing too.

Overall, I think this antenna is worth a purchase if you have some Amazon points or other disposable funds anxious to leave your ownership. 


Kenwood TH-D74, Alinco DJ-MD5XTG, Lanch HG-UV98, APRS, VHF 2m loop antenna, HYS, HVDN, DMR, amateur radio SHTF
Your mother told you NOT to stare, right?  Here are some of the things used during the test
(Source:  Steve Bossert K2GOG)

Sunday, March 6, 2022

CHARGED UP REVIEW: Lanch HG-UV98 Battery & Cradle Charger



Way back in October 2019 was my original review of the Lanch HG-UV98 dual band VHF/UHF analog APRS radio. 

Now it is time for a little bit of an update regarding the battery life.

Since my original review and a bunch or other related articles, I have purchased a second radio because it is good to have a spare on hand just incase.

This obscure but affordable radio has proven to be a great "field friendly" radio for times where the more expensive APRS capable Kenwood TH-D74 is not worth taking a risky drop while scrambling up a hill or in the snow.

While the vendor website is no longer in operation for Lanch, its distributor Venus Information Technology has provided excellent support even during COVID times and has many in stock and offers the software for programming too, which can also be found on HVDN as well.

Included with the original Lanch HG-UV98 purchase was a USB car and wall charger plus one USB micro cable.  To charge the radio battery, you simply plug in the charge to the port on the rear of the battery. 

As you can see below, these accessories never even left the box since I had many other chargers to use already on hand!




24 Months:  Battery Review

There are not many amateur radio's that can charge over USB power even in 2022, so considering that Lanch offered this feature in 2019, this was a major benefit feature to have for interoperability.

Just before Winter Field Day 2022, my original HG-UV98 battery decided to "puff out" which meant it was time to order up some spares. 

The below photo shows my disassembled battery which inside is a pair of 3.7V 2500 mAh capacity cells held in place by adhesive tape as found in many other battery packs. Only one of the cells seems to have malfunctioned though so I have plans for the remaining good cell.


Two series 3.7 Volt 2500 mAh LiPo cells can be found inside the Lanch HG-UV98 battery (Source: Steve Bossert K2GOG)
Two series 3.7 Volt 2500 mAh LiPo cells can be found inside the Lanch HG-UV98 battery
(Source: Steve Bossert K2GOG)

The insides of the battery also includes a USB micro converter and charge controller so these will likely find use in some other DIY project later on, so DO NOT throw out your old battery when it eventually fails! 


A USB micro charge converter can be found inside the battery along with a charge controller
(Source: Steve Bossert K2GOG)


Talking about the new charge cradle

In mid 2021,  my contact at Venus Information Technology let me know they had developed a charging cradle for the radio and were offering that plus a battery for sale for only $32.60 USD.

On February 22nd I placed the order and on March 6th the package of charger and a few extra LC-01 batteries arrived from China. Lets now look at what arrived!


Blackberry USB micro cable Lanch HG-UV98 APRS radio
Recognize the logo?  A former smartphone vendor must have had a
surplus of USB cables that Lanch has found a second life for!
(Source:  Steve Bossert K2GOG)

Lanch HG-UV98 Battery Cradle Details

Here are three photos of the new cradle, clearly showing it is designed to be charged with USB micro connections.  You can charge the battery without attaching it to the radio if needed.

The cradle only comes with a USB micro wire and no USB charger, but that is ok as I already have left over ones from past or other purchases.

The label on the bottom of the charger helps validate that the battery does the conversion from 5V USB standard up to 8.4V needed to charge the battery.  

But, interestingly the inside of the charge cradle has its own voltage converter. When the battery is charged in the cradle, the internal battery converter is bypassed.





Extra Bonus Details

Electronic devices these days often have shorter life cycles so that vendors can sell new equipment, but that is sometimes wasteful.  

The good news is that the Lanch HG-UV98 will soon be joined by a new radio which combines the APRS and radio programming into one common MCU.  

This means no need for two separate computer  programming applications.  Both radios will use the same battery which is the major extra bonus!

Support these products!

Normally, I do not outwardly endorse a vendor product, but in this case I will.  Based on the behind the scenes support from Venus Information Technology and a lack of other reliable low cost analog AX.25 1200 baud radios, the Lanch HG-UV98 will be a great addition to anyone looking for a first or additional APRS radio.


Wednesday, February 9, 2022

Huge Packet Loss: WB4APR goes SK



Bob Bruninga WB4APR has left a huge impact on the amateur radio community and will be missed greatly.  His legacy as the inventor of "Automatic Packet Reporting System" or APRS for short created entirely new product categories and use cases for low speed packet data dating back to the late 1980's. 

Almost 40 years later, the use of APRS continued to evolve and Bob was still very active in giving presentations and sharing ideas on how else to use this aspect of amateur radio even after he was diagnosed with cancer in 2020. His passing in February of 2022 was not a surprise, but something many hoped would not happen.


K2GOG's Kenwood TH-D74 receiving Bob WB4APR 
while traveling in Connecticut in 2017.

Remembering WB4APR: K2GOG Memories

Before I became a licensed radio amateur, a friend of mine, Scott WA2INP but was KB2UZQ back then, had an uncle James KB2RSB who was interested in connecting computers to radio.  

In the late 1990's, the internet was not what we know it as today and amateur radio "bulletin board systems" or BBS's were popular ways to share information across a network of VHF packet gateways on Long Island where I grew up. 

While most people at the time were using packet BBS from home, James was doing this from his car with a laptop, mobile radio and modem.

This was super interesting to me and I was motivated to make the jump from CB to amateur radio because of this moment in time.

Just a few years later, Kenwood released the TH-D7a handheld radio which had built in APRS and packet communications. I saved up money from my job at Radio Shack and traveled into Manhattan to Barry Electronics to purchase this new radio.



The owner, Barry, was surprised someone of my age (19?) has the cash to afford this expensive radio and wanted to make sure I could pay for it before he got it from his inventory. I forked over my obscene amount of cash for the radio, spare battery and speaker mic. My parents were not happy on how much money I just spent on my new hobby.

Playing with this radio on the Long Island Rail Road ride home was my entry to the future and something that even inspired my career which included LBS engineering at Sprint after leaving Radio Shack and before diving into the market research/advisory world I have been in ever since, focusing on commercial telematics and location aware technology among other things.

Soon after getting the battery charged up after the long train ride home, I connected the TH-D7ag to a Sharp OZ-770 pocket organizer which had serial terminal features.



Quickly I was then using the tiny organizer connected to my radio to connect to the local packet BBS. I think the first thing I downloaded over that 1200 baud connection was a basic overview of APRS.

A few pay checks later, I went to West Marine and purchased a Garmin GPSIII.  This was an early portable GPS unit which was as big as the Kenwood radio itself.  Connecting the GPS with a mess of bulky cables to the radio gave me the ability to share my location with other radio amateurs and share text messages back and forth. Demonstrating this at the LIMARC ARRL Field Day in 2003 amazed many people who could watch my location in real time as I rode my bike around the Field Day site and the signal was received by Rich N2STU, SK back under the shaded operating tents with computers.


Considering by 2004,  its crazy to imagine how far things have come since then about APRS. I have done so much with APRS over the past 17 years which is best saved for another day.

I have two parallel paths in the early 2000's which meant I could take my Motorola StarTac phone and connect it to my organizer to access the internet at a blazing 19.2kbps or use my ham radio gear for other communication needs.

Ever since that time, it has been fascinating to watch how mobile broadband and location aware communications has evolved in the commercial world as well as for the normal every day consumer with our smartphones today.

Over the years I would have occasional communication with Bob on a range of topics hobby and non hobby related, but still focused around situational awareness.

I owe a lot to Bob WB4APR for his contributions and he will be missed!

Lasting Impact of WB4APR

The amateur radio hobby has lost a huge asset and Bob will truly be missed.   While HVDN was only formed in 2017, APRS has been a very popular topic on our blog as the third most popular tag behind "DMR" and "SDR".  Here is a short list of some of the APRS focused articles to show how wide an impact Bob has made just in the last few years.

Monday, November 29, 2021

Doing "data stuff" over VHF/UHF FM?

First, let me set up a user scenario so this makes sense as to what problem is being solved.  

Imagine you are somewhere where you have a fully charged smartphone, but no network access of any kind along with a dual band handheld amateur radio.  

Aside from the above, you happen to have some type of HF radio with you, but you forgot a few important things at home like a Morse code keyer and some important thing that prevents you from powering your HF radio, like a power cord, fuse, etc. 

Your only method of outside field communications is with your handheld radio now! 

Luckily, you have a few extra things  with you such as an Easy Digi Interface and a USB-C to 3.5mm adapter with you. How can you communicate using non-voice modes?

Sending certain data signals over FM provides some benefit. Lets explore a few of these where you will be connecting your smartphone to your handheld radio.

Smartphone Headset Adapter

If you have a smartphone with a headphone jack, that is great but is feature becoming less common.

The latest Android or Apple devices have done away with the standard 3.5mm headphone jack and is why you need an adapter that goes from USB-C (Or Lightning) to a 3.5mm jack.

For $9.99, this USB to 3.55mm TRRS headphone adapter gadget can be yours and will find many other uses you can think about.  Support fellow Hudson Valley club OMARC by using Amazon Smile.



Easy Digi Interface

This simple box allows you to connect your smartphone to your handheld radio.  You may or may not need the smartphone headset adapter, but lets pretend you do.  

It is now simple for you to connect your radio and smartphone together thanks to KF5INZ and the appropriate version of his adapter for your radio. Below is pictured the version appropriate for the Alinco DJ-MD5XTG DMR radio along with the USB-C to 3.5mm TRRS adapter.

An alternative option, but still using a different form of the Easy Digi Interface was even written up by HVDN's Joe NE2Z back in 2019.

Do Not Leave Home Without Software

Since you do not have network access to download applications on your smartphone in this described scenario, install a few before you get stuck somewhere.  

The first application to focus on is one that you can send pictures with.  SSTV and its different modes offer different benefits and this ability might come in handy to increase situational capabilities.

The second application to focus on is something that can send text data in a conversational format.  Modes like RTTY and PSK31 are great for this as they work just fine being sent over FM.  Small or large amounts of text can be shared with these modes. VARA FM is not a focal point in this article since we are focusing on basic implementation for basic users.

A third application is something where you can share your location and short embedded messages.  APRS.  APRSdroid is a great way to start related to APRS without a dedicated APRS radio. 

Here is the list of essential communications applications you should have on an Android device relative only to the use case described in this article.

Please note that similar versions exist for Apple devices, but HVDN can not provide comment/support on those, but we welcome your Apple favorites. 

Robot36 - Highly Recommended as SSTV reception application because of modes supported like PD50.

SSTV Encoder - Recommended for SSTV transmission via supported modes like PD50

APRSdroid - Highly recommended for sound card based APRS with appropriate interface cable.

droidRTTY - Recommended for RTTY over FM or other modes.

droidPSK - Highly recommended for send/receive of PSK using appropriate interface cable.

droidSSTV - Another SSTV option, but better options exist. 

AndFlmsg - Many supported modes but experience may vary based on your smartphone/tablet.

Wednesday, October 27, 2021

APRS with your Alinco DJ-MD5XTG or Anytone AT-D878UVII


How do you send analog APRS with your Alinco or Anytone radio?   This video explains how to configure your radio. 

Please note that while this video focused on the Alinco DJ-MD5XTG, the basics will apply to the Anytone AT-D878UVII as well.  Sweet! 

There are earlier versions of both radios that could not support this feature as noted in the Alinco DJ-MD5XTG teardown as well as on Jason's fantastic page about these radios down in VK land. 

It is worth noting that the latest Anytone AT-D878UVIII supports analog AX.25 APRS reception via an additional circuit board. 

Alinco does not offer this on its latest XTG model, but having packet transmission capability is still great to have. 

Sunday, August 1, 2021

What the heck is APRStt?

APRStt

What is this article about?

APRS stands for automatic packet reporting system and "tt" stands for "touch tone".  Most "radio hobbyist" people have heard of these two acronyms before, but not used together.  The goal here is to explain simply how APRStt works.

APRStt is not APRS

APRS typically uses analog 1200 baud AX.25 communications that in its most simplistic form, is not very different than how modern internet works. There are headers, body, routing and other message portions that help identify, deliver, acknowledge and add value to a sent or received message.

APRStt by comparison is only made possible by some infrastructure that can decode a string of touch tones known as DTMF. Dual tone multi frequency is the same as found in telephone communications for more than 50 years.  

When you press the appropriate button, your radio sends a combination of two tones below at the same time, such as the "5" key would generate both 770 Hz and 1336 Hz.

aprstt

When a radio user transmits the appropriate tones, the receiving infrastructure can decode these tones and convert them to useful information such as location and status reporting that can appear on a computer screen or certain radio equipment. That essentially is how APRStt functions.

Most any radio with a keypad will include DTMF functionality and thus offers a unique capability for control or reporting via APRStt if you have the necessary receiving infrastructure from even the most inexpensive of radio, like the popular Baofeng UV5R. 

Use Case #1 for APRStt: Remember the game "Battleship"?

One great example to help explain APRStt is the classic game of "Battleship" where players ask the opposition if they have a ship located in a letter and number sequence grid, such as "B5" or "FOXTROT 9". Since this is a known location on the game grid, its easy to confirm location and score either a hit or a miss.

APRStt can work the same way.  If you transmitted a DTMF string such as *13316248302228#, that would translate to the callsign N2HVD along with maidenhead grid square of FN31.   The maidenhead system is used just like GPS coordinates, but offers a more general location in a 70 by 100 mile box.

Today, there is a satellite called PSAT2 that offers the ability for a ground user to transmit a formatted DTMF sequence on 145.980 MHz and if that message is received by the satellite as it passes overhead, the ground user will hear a computer voice acknowledgement on 145.825 MHz to confirm the contact  exchange.

To dive into the super details on how *13316248302228#  is calculated, you can read more at:  http://aprs.org/psat2.html 

aprstt

Use Case #2 for APRStt: Supporting a local event

Being able to share location information like this can be applied to many real world applications such as for finding people at a special event like a large festival or even a race where not everyone will have an expensive APRS radio, but does have a DTMF capable radio.  

Here is an example by the inventor of APRS, Bob Bruninga WB4APR as deployed at the Dayton Hamvention in 2010.

aprstt

Making APRStt work for a marathon or other race?

Rather than thinking in terms of a location grid, another way to use APRStt is to set predefined locations long a race route which matches GPS locations.  

When a user transmits a number sequence, the infrastructure can receive a DTMF string which may identify a race mile marker, athlete status, health condition and unique "bib" number.  Here is an example as set up for the upcoming United States Military Academy triathlon. 

aprstt



Once the ten digit DTMF sequence is received and decoded, the infrastructure can transmit back a computer voice to let the support staff know the message was received, but the infrastructure can also translate this to be shared over the APRS network and appear on a map in real time. 

APRStt, aprs touch tone,  aprs dtmf, usma, usma triathlon

How to make your own APRStt infrastructure?

In a follow up article, we will detail how to combine a radio with a computer interface along with the appropriate software to create your own APRStt infrastructure for your own local area or special event.

Please follow the N2WU.com blog for more on the technicals behind this with a special focus on the software and tips on ensuring a fully functional system via lessons learned by the 2021 USMA Triathlon which is taking place on August 15th 2021.

APRStt

Monday, May 3, 2021

UPCOMING 5/17/2021 HVDN:LIVE - Putting balloons into the sky with USMA



On April 27th 2021, the United States Military Academy at West Point put its 11th Astronomy Club and Amateur Radio Club balloon up into the atmosphere of the Hudson Valley and reached 80,000 ft.

Cadets Raymond Triggs '24, Rathin Shah '24, Jacob Willis '23 and Nolan Pearce '22 KE8JCT led a team of fourteen cadets, four of which also have amateur radio licenses.  A total of seven USMA faculty members, including  MAJ Robert Perezamemany and COL. Stephen Hamilton KJ5HY, MAJ Ben Popko N2IAV and Dr. Kate Duncan KB2ZOO helped make this years mission a success.

CDT Nolan Pearce '22 KE8JCT

Please join HVDN: LIVE on May 17th at 8:00 PM EST for a detailed overview of this project

CIC(Cadet In Charge) Pearce will cover the design, build process, launch and recovery of the 6 lb.  STEM focused payload which  included:

  • VHF APRS
  • GPS
  • SSTV
  • GoPro camera
  • Space beer? (Wet yeast!)
  • More....
Cadet Pearce will share details from this years launch over a 30 minute presentation with audience questions saved until the end.

Nolan is active within the USMA radio club W2KGY which will also be participating as N2D during Hudson River Radio Relay this year and he also has a rather excellent blog covering many topics of interest to the amateur radio community.

How to attend?

This presentation is free for anyone to attend via the free open source Jit.si application and will also be live streamed on the HVDN YouTube Channel.

First 50 guests can join via https://meet.jit.si/hvdn/livemay2021 and use password = helium

Additional "human" attendees can follow live or during the replay on the HVDN Video Channel