Fishing In the Woods: Looking for Radio Signals

This was the first Winter Field Day that justified a reason to purchase an ice fishing tent.

The tent manufacturer claims you can set this up in under a few minutes and pack it up even quicker.  Lets see what the breakdown looks like.

 

Inside the Tent:  Gear needed

We all like lists right?  Here is what was in use in the photo below.

• Icom IC-705

• Emtech ZM-2 Manual QRP Tuner

• Heil HTHD-Y headset

• Lenovo T495 laptop

• 12aH DIY LiPoFe4 battery pack

• Polaroid Brand Travel Tripod

(Photo Courtesy:  Ken Campbell AD2T)

Excluding the table, chair and propane heater, this was a minimal operation which proved pretty comfortable even in the low temperatures during Winter Field Day.

The goal was to operate 10m or 15m  PSK31, JS8CALL or SSTV but most of the time it seemed that FT8 was more popular, so that would not count for Winter Field Day. Too bad!!   The 15m band was wide open which was really nice.  A few contacts were made on 40m SSB, hence the need for the headset.

Antenna Questions

A 40m Off Center Fed home made dipole was used with good success.  This design allows for 40m, 15m and 10m operation without really needing the tuner..  One leg of the dipole is 44 feet and the other is 22ft.  At the center point is a 4:1 DIY balun.  The antenna center was mounting with velcro ties on the 20ft orange Jackite fiberglass mast.   

The mast was secured to the ground with a ground stake and length of PVC pipe which the mast simply slides over.  The longer end of the dipole was attached to a nearby tree with a length of paracord.  The shorter end was attached to an artificial tree known as a tripod.

Even with heavy winds, the antenna system as expected maintained upright for the 24 hour event in the frigid cold!

This antenna system works great and easily stows in a bag designed for audio equipment.  Many other accessories for additional HF and VHF antenna also fit in this bag along with a few 25 and 50 foot RG-8X feedlines. 

I would estimate that my entire antenna kit which includes the storage bag, surplus tripod (RIP KE2EJ), feedlines, support stake, full wave 2m loop, Arrow II antenna, 40m OCF, 10m-17m-20m-30m linked dipole,  End Fed 40m/80 and a few other odds and ends cost less than $200.  This is a lot of antenna gear for different applications mostly meant for POTA operations and not SOTA activity which is much smaller scale.

(Photo Courtesy:  Ken Campbell AD2T)

An article like this can get really long if I wanted to detail how to set up Wi-Fi on the Icom IC-705 to talk to the laptop with virtual com ports and audio cables, but there are great tutorials on YouTube which cover that already.  

The only issue I really ran into which continues to be a level of annoyance is that the "705" has such a broad front end that semi decent antennae can easily overload things, so backing the RF gain down is a good idea.  

Nearby strong out of band signals also are problematic and an external band pass filter will be needed for the 705 to perform better during group special events like Hudson River Radio Relay coming up in June..

Last year during that event, the 705 on the 6m band was useless when nearby 20m or 40m CW and SSB activity was taking place.

Not really sure if this article answered any questions for anyone, but it was fun setting this up for Winter Field Day and spending some time playing radio plus teaching others about how to set up a minimal self contained field station.

Recipe for Success: What is RTTY?

Radioteletype or "RTTY" is a digital data mode that allows text to be sent over radio and has been around since the 1930's.   

Before RTTY signals were sent over wireless, teletype was used going back to the mid 1800's which makes this one of the oldest modes of non-spoken communication, just like Morse Code.

Within amateur radio, RTTY is commonly sent on HF bands by using 45.45 baud at 170 Hz shift width along with a mark frequency of 2125.  It is also possible to use RTTY on all other bands such as the popular 2m band and at even greater speed. What does this all mean?  Lets find out.....

RTTY Basics

The term "baud rate" is used to explain how many words per minute can be sent and there are 60 (45.45 baud), 67 (50 baud), 75 (56.25 baud) and 100 (75 baud) options as standard within amateur radio.  

Here is where sending large amounts of data really started thanks to RTTY since even trying to speak more than 60 words a minute may be a challenge for many people.

If you think about how that translates to 1200 baud which is what APRS uses, or the last generation of "dial up internet modems" in the late 1990's which used 56,000 baud and now, all the way to modern broadband which would be too fast to even easily think about, RTTY sounds pretty interesting, right?

Some of the earliest RTTY activity took place just down the Hudson River on Long Island and a brief history is available on the RTTY Wikipedia page.  Lets keep building on our regional history by keeping RTTY alive! 

Here is what a RTTY signal would look like and how the "mark" and "space" are visualized.

Each of the signal peaks are one of opposing tones that help identity bits in the symbols being sent which translate to letters, numbers and special characters.

While there are more efficient modes of "keyboard to keyboard" communication available today, RTTY is not only reliable, but easy to be sent with basic equipment.

We learned with SSTV experimentation during the weekly UNDR Net in September 2021 over the 146.805 MHz repeater operated by the Overlook Mountain Amateur Radio Club, its possible to send images, so now its time to send some text.

RTTY takes up around 250 Hz of receiver bandwidth if your radio is set for 170 Hz shift between the high and low tones. This is more than ok if you plan on sending RTTY over FM since a typical signal is 25 kHz wide, so there is more than enough room to send RTTY over FM.

The year 2021:  Why RTTY?

While RTTY is mainly used during special contests or between just a few friends, its still a mode that is worth keeping in your communications tool box.

A benefit of audio frequency shift key (AFSK) based modes is that they are easy to decode simply by holding a smartphone near your radio speaker. You can even send RTTY by holding the microphone of your radio near the speaker on your smartphone.

Better results can be had with a wired interface like the Easy Digi device for use with most any handheld radio or the Masters Communications Model RA-40. 

Some radios even include a built in decoder for RTTY like the Icom IC-7000, IC-7100 and IC-705. 

As we learned by sending the PD50 SSTV mode which takes about one minute over FM,  this should mean we can send at least 60 words of text or more in the same time using RTTY.  This capability could be very useful in certain situations where accuracy counts and a digital signal is better than speaking.

What if we wanted to share Uncle Grants Field Day Chili recipe over the air?  

According to the below photo courtesy of the ARRL, this recipe page has 313 words and it may actually be quicker sending a recipe like this over RTTY compared to multiple smaller sectional photos sent over PD50 SSTV or one higher resolution photo using the PD290 SSTV which would take almost 5 minutes!

The above recipe can certainly be condensed and reformatted for more "human readable" reception if sent over RTTY.

This will be one of our first tests in sending some interesting information using RTTY in the month of November during the UNDR Net.

If you are interested in joining our experiments, feel free to come up with your own interpretation of the above recipe and lets see who can transmit it the fastest that is human readable on the receiving end. 

Please join us every Tuesday at 8:00 PM Eastern US time in the month of November to listen in or participate with what we are doing each evening with RTTY.

IMPORTANT:   Starting December 6th 2021, UNDR Net will be moving to Monday 8:00 PM