Tag: APRS

Posted on

APRS RX-only I-Gate

What it does:

This station listens for and decodes APRS packets from other stations and “gates” them to the internet. These other stations can be mobile (vehicle or pedestrian) or fixed stations (like digipeaters).

When APRS is being used, any other APRS-capable radio can decode the packets being sent out (either natively on the radio, or through connection to a computer of smartphone). So if you and a friend are using APRS in the middle of nowhere and are within simplex range of each other, you can receive positional information or messages on your radios from each other.

But that only works for certain things. If you’re looking at using APRS for tracking your buddy, but they’re outside of simplex range, you would need to employ a digipeater. They listen for APRS traffic and re-transmit those packets to a wider area. This is very similar to how regular amateur repeaters work for voice operations. The repeater is in a prime location and can usually transmit at a higher power level using better antennas for better range. APRS paths usually allow for multiple hops between digipeaters to not only help with range, but also to allow for a higher chance of being picked up by a station running an I-Gate.

Which brings us to I-Gates!

Now, for example, if you’re looking at tracking your progress during a roadtrip, then an I-Gate is a must! Some digipeaters have them built-in already, while others do not. It depends on what equipment is available to the digipeater owners, the local network needs, and a few other factors.

If you traveled from Montreal to Las Vegas and were firing off packets every 60 seconds or so, there should be stations well away from your location that can see where you are. The only thing is, those packets are heard, displayed when received (maybe logged in a file somewhere), and that’s it. Throw an I-Gate station into the mix and everything that it hears is uploaded to the internet. Connecting to the internet allows positional information to be viewed on sites like aprs.fi.

That’s what this thing does:

Behold, the glorious RX-only I-Gate!!!

This I-Gate regularly receives packets digipeated from VE3OCR-2 in downtown Ottawa, as well as simplex packets from nearby mobile stations. Checking the information for VE3OCR-2, it can be noted that it is not gating any data to the internet, just repeating it back out over RF.

VE3OCR-2 only shows info about packets heard directly from other stations

There are other stations in the area that digipeat AND gate, such as VE3SHQ located at the Scouts Canada Museum further to the west.

VE3SHQ shows info about packets heard directly AND packets sent to APRS-IS (the internet)

And then you have my IGate. It does not digipeat over RF. The only thing it does is listen for packets, and then upload them to the internet.

WNX-10 shows info similar to VE3SHQ, it just can’t transmit over RF

Ok, it actually does a bit more than just that. I do have a set of repeaters set up to display on aprs.fi and when I go camping and plan on doing long range testing, I usually place markers to help others see where I will be operating from. There are even airport markers that I was testing out awhile back too.

This I-Gate is set to beacon every 30 minutes. I’m not entirely sure if that position is sent out through other digipeaters with an I-Gate or not (pretty sure that’s an option that can be enabled/disabled by each digipeater). Not that it fully matters as it shows up on aprs.fi and likely isn’t of much use to anyone to know where it is anyways, It’s more akin to behind-the-scenes infrastructure than anything else.

The parts:

  • Asus EeePC 1000HE (running APRSISCE32)
  • Realistic PRO-2037 desktop scanner ($8 in box from a local thrift shop)
  • N9TAX SlimJim antenna
  • 3.5mm aux cable (audio-out on scanner >>> audio-in on computer)

This setup takes up a bit of space and it could definitely be run on a Raspberry Pi with an SDR dongle instead, but I appreciate keeping old tech alive and running. The laptop is from 15ish years back and is woefully inadequate for running most modern software and the scanner is from sometime in the mid-90’s, but it’s a scanner. It just sits and listens on whatever frequency you point it at, and it just works. The SlimJim antenna is hooked into the BNC port at the rear of the scanner (not pictured) and is currently strung up in a nearby window in a very temporary fashion. A second SlimJim will be arriving in the next few weeks with a 16′ length of coax so that I can hard mount it outside the apartment. That being said, I’ve been blown away by how well the current antenna setup receives packets over the stock telescopic antenna that came with the scanner, even with it being mounted indoors.

Below is a comparison of the receive-capability of the setup from 2 different months in 2024:

Reception range in October 2024 using default telescopic antenna
Increased reception range in December 2024 using SlimJim antenna

At some point in the future I’d like to deploy a full digipeater + I-gate solution, but that’ll have to wait until I can find a decent QTH location much further out from other local digis.

Posted on

Manpack Radio UPDATE

The manpack radio setup is complete (and honestly has been for some time now)! The remaining bits that I needed were a shorter length of coax to connect the remote antenna connector and a LiFEPO battery. I opted for a 1 foot length of LMR-195 (slightly less loss and more rigid than RG58) and a 9Ah Bioenno battery. I did also opt for a N9TAX SlimJim antenna for this kit. An in-line power meter was also added to the setup. For some reason Yaesu decided not to have the voltage be available on the radio’s screen for some reason, despite it being available on rigs of the same age and class as this one. Bit of a failure there, IMO.

Thanks Yaesu. I appreciate the extra bulk

I managed to get out for some testing at various points throughout the summer in its mobile configuration (just the radio sitting in the shotgun position in the car) with some good results. I also ended up taking it with me while I camped at Ferris Provincial Park in September to see what kind of range was possible with this rig. I chose Ferris because the campground is on top of a drumlin and would have better line of sight to distant stations

The antenna used for testing was the Arrow II. I did have the SlimJim on hand, but wanted the best range possible this time around. The SlimJim has been tested previously and was found to work decently in an urban environment with stations fairly close.

Nerding out in the dark. Yep, this is my life

The results of my testing are below:

Day 01 – 25W Output:

  • VE3PBO (Peterborough) – S9+. Contact made during net.
  • VE3CKL (Lindsay) – S1. No QSO.
  • VA3FOY (Bancroft) – S2. No QSO.
  • VE3BNI (Gilmour) – S4. No QSO.
  • VA3LTX (Dysart) – S1, heavy scratch. Unable to open repeater, but able to listen.
  • W2RUI (Lockport, NY)- S0-S7. Tropospheric ducting. Attempted contact up to 50W but not heard.
  • VE3KFR (Campbellford) – S9+. PROCOMM net in progress, listened only.
  • VE3RTR (Rice Lake) – S9+. PROCOMM net in progress, listened only.
  • VE3QAR (Belleville) – S2. PROCOMM net in progress, listened only.
  • VA3JWO (Picton Wide Area) – S9. No QSO.
  • VE3TJU (Picton Airport) – S5. PROCOMM net in progress, listened only.

Day 02 – 25W Output

  • VE3KFR (Campbellford) – S9+. Contact made, participated in the Professional Loafers Net.
  • VE3TOR (Scarborough) – S5. No QSO.
  • VA3ROG (Collingwood) – S0-S4. Tropospheric ducting. Station ID’d numerous times as WRQROC, and had a VE3 net controller, but not able to find any info on what this is, so assuming it’s VA3ROG due to its large footprint. No QSO.
  • VA3JWO (Picton Wide Area) – S9+. Contact made.

After 3 days out running at 25W, including 2 days at camp and 1 day operating mobile from the car, this rig only used 5.78 Ah of juice from the battery’s 9Ah capacity. This was with APRS firing away every 60 seconds on the second VFO while driving and sporadically (likely every 10 min or so) while at camp, and with voice being used as well.

APRS track for the return trip home

The weekend prior to the above outing, I was out and about with the manpack. A single packet was received in Pennsylvania on its first hop by station N3TJJ-7, a total of 257.7 km away. To date, this is the furthest simplex contact I’ve been able to make (automatically sent, but I still count that) and was very likely due to tropospheric ducting and also helped by the elevation of both the transmit and receive sites.

Furthest contact to date!

All results from my testing have been added to the page for each respective repeater on Repeaterbook.com.

Posted on

Manpack Radio Project

New year, new project!

My main goal with amateur radio (at this time) is to push standard VHF and UHF (non-SSB) comms to their limits, but there is only so much you can do with a handheld yagi antenna attached to a 5W handie-talkie. I had experimented with long range stuff during my voyage to Main Duck Island in August 2022 and had some good results. The thing is, this was over mostly open water and shoreline, likely bolstered by some tropospheric ducting over such terrain. This was handy, but I normally don’t operate in that type of environment. According to K0NR’s website and book (VHF, Summits and More: Having Fun with Ham Radio), more range is usually possible with a better antenna (which I already have) and with applying more power.

There is also a chap on the Tube of You that goes by the handle “The Tech Prepper” who has come up with a modern take on manpack field radios used by the military. A concept that I had been thinking about for some time, but without any decent idea of how to make it work properly. He has a series of mobile and HF radios fitted with custom rail kits that allow mobile-style radios (those you would normally mount inside a vehicle) to be taken anywhere and used similarly to how an HT would be used. This gives the ability to use more power than you normally would be able to for a VHF/UHF field deployment.

I purchased a Yaesu FTM-200D in September 2022 in preparation for this project. I snipped the power connector off a week after I received it and fitted it with some powerpole connectors (there’s no going back now!)

Yaesu FTM-200D Powerpole-Equipped
Powerpole-equipped

It took me a few months to get around to it, but I finally ordered a set of rails from Armoloq and fitted them to the radio. The basic rail kit consists of an aluminum rail for each side of the radio and an antenna relocation mount. I chose this radio as I wanted to use it in the field, as well as my vehicle, and wanted to have APRS capability built-in to reduce the amount of extra stuff I’d need to carry. I do use APRS on the reg. If I need to do any other fancy-crazy digital modes, there is a data port on the rear of the radio. The radio so far has only been powered by the solar box I built and I plan on upgrading to a LiFEPO battery setup sometime in the near future to reduce the size and weight. The radio is capable of transmitting with 50W of power, but will only be used in manpack configuration at either the 5W or 25W settings (I’d like to not die from RF exposure anytime soon).

Yaesu FTM-200D Armoloq TPA-300
Rail kit attached with antenna relocation mount up top (cable not included)

A new antenna will need to be procured to make this setup more compact. I’m looking at picking up a Slim Jim antenna and running it up a collapsible carbon fishing rod. This will be way lighter and more compact than the Arrow II mounted to a tripod. The goal is to be as efficient as possible, while not dying after sliding down a slope and being buried by my gear.

Yaesu FTM-200D Maxpedition Colossus
Fits in my Maxpedition Colossus with some space on the sides. Just need to remove the antenna to zip up

The antenna relocation mount can be attached anywhere on the frame kit and is currently setup with a coiled up 3 foot section of RG58 until a shorter length arrives at a later date.

More to come as the parts come in.

Posted on

International Space Station SSTV Status

There haven’t been any SSTV events from the ISS recently, this being due to new laptops being deployed to the station and the Russian segment (where the gear used for SSTV transmissions is located) not having a proper interface for connecting the radio to the newer computers.

This issue was noted on the ARISS website on December 22, 2022. There’s usually a bunch of Russian SSTV events (usually planned around times when the station is primarily over Russia, unfortunate but understandable) and to a lesser extent some standard SSTV events around the holidays and earlier in the year.

All that being said, the radios on the station are still available for other uses. The radio located in the Columbus module is in a crossband repeater configuration (of which I was completely unaware of until a few weeks ago) and the radio onboard the Service module (likely the Russian module mentioned earlier) is configured for packet data.

I was able to send some APRS packets to the station on December 30, 2022 and they were picked up by VE2UAL-2 in Quebec and K4KDR-15 in Virginia.

The station is usually in the sky for around 10ish minutes during a really good pass, likely that this 800+km APRS contact could also be duplicated using the crossband repeater

I’ll need to do a check for the best ISS passes for next weekend as I’ll be winter camping and will have plenty of time to mess around with the radios. I’ll definitely be testing out the crossband repeater functionality.

If you go here, you can check out the status of the onboard radios. This also includes info on planned shutdowns for docking/undocking procedures with supply ships and what-not.

Posted on

ISS Contact

A few months back, I purchased an Arrow II satellite antenna so that I can get better results when the International Space Station has their SSTV events. There are usually only a handful of events each year, and I’ve missed most of them since the first one I participated in back in February 2019.

The station has its own APRS setup, so I decided one night to see if I could ping it with my equipment. I used APRSDroid on my phone and linked to one of my UV-5R radios. All that needed to be done was to change the APRS digi path in the app preferences menu to ARISS and set the frequency on the radio to 145.825 MHz. All I could do then was to eagerly wait for the next pass of the station overhead.

SUCCESS!

The following image shows the contact. Only 1 packet made it through, though I had made several attempts during the pass. The packet was digipeated back to Earth through KE8FZT. This was a fun experiment and I look forward to attempting it again with my big old tripod I dug out of storage a few weeks back. Should make things a bit easier going forward.

Screencap shows the default ISS position out near the west coast of Africa (it’s always there). It was almost directly overhead when the contact was made.

Note: Yep, don’t start a post while you’re falling asleep. It’ll end up sitting as a draft for a few months if you do.