VK8MT - Amateur Radio projects and Other Stuff by an Introvert Communicator
Nothing stays the same. This is the case for my Remote Station which has now morphed into a remote receive only HF & VHF iGate. After acquiring an SDRPlay RSP 1, I have now removed the IC-7300 and replaced it with the RSP 1. So now the remote consists of the NUC, the preexisting RTL-SDR and the SDRPlay RSP 1. This allows me to run APRS iGates on 30m and 40m using the RSP 1, and 2m terrestrial (145.175Mhz) and 2m satellite (145.825Mhz) using the RTL-SDR.
Dealing with audio from the two devices created some challenges, however these were overcome as the DireWolf APRS software can accept UDP connections. I am using SDRuno for the HF side, running two virtual receivers, piping the audio via a virtual audio cable using the left and right channels for the 30m and 40m audio, respectively. I am using the SDR++ software for the RTL-SDR, as this allows for UDP audio streams. This software can also run multiple virtual receivers (to separate UDP ports). Problem solved!
The DireWolf software is a very remarkable piece of software, which just seems to work without fail for years at a time. I have used it mainly on a Raspberry Pi running Linux for probably over a decade. It seems just as stable on Windows 10. Given that APRS on HF is using SSB DireWolf has the ability to setup multiple receiver pairs with filtering. This can be seen in the screenshot below.
It seems that the processes can only handle so much as I needed to reduce the number of receive pairs on the 40m side. Nonetheless, this is still impressive.
The 2m side is working well, having received signals from both land and satellite sources. And the HF side works on the test-bench. One thing that is still required is the setting of audio and receiver gain levels, however I think I am getting close.
That's it for now.
Cheers
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| Click in image to enlarge. |
A change in my work role means that I will be travelling our to remote communities regularly. As a safety precaution the company require me to have some form of satellite communication. There were a couple of options that I was looking at, one being the Spot range and the other, the Garmin range. I was aware that there was a way of getting the Spot beacons onto the APRS network, and so initially I was leaning towards the Sport X. However I have owned a number of Garmin devices over the years and always found them to be well made.
So, after much research I decided on a Garmin inReach Mini 2. This devices used the Iridium satellite network. The device itself is small yet can do so much. It will beacon its position at regular internals (10, 20 &30 min) and it also allows for unlimited 'check-in' messages and also two way text messaging. It can be used stand alone, but is much easier to used when paired to a smart-phone via Bluetooth.
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| The inReach Mini 2 beside my ID-51A |
It turns out that the guy who wrote the code for getting Spot beacons onto APRS has also written code for the Garmin inReach. Enter Mark VK5QI.
Mark is a very active Amateur Radio enthusiast. (And I suspect active in lots of other areas as well.) His website can be found HERE, this is more for getting an idea of the kind of things he get up too, but don't expect regular post. The last post is a couple of year old! However, he has written huge amounts of code, and this is where our paths have again crossed. I say again because Mark helped me out years ago when I was registering my D-Star radio, and then again when I was playing around with tracking Weather Balloons. Anyway, it turns out that he is the author of some code called inreach2aprs (and also for that matter, spot2aprs). The code can be found HERE.
This code sends a queries (or request) to the Garmin website and received the position data, which it then processes and converts into an acceptable format for the APRS network. Easy!
A simple bash script (sat2aprs.sh) is called via crontab at predefined intervals (in my case every 20 minutes).
sat2aprs.sh
#bin/bash
If you want to change the APRS symbol this need to in modified the inreach2aprs.py program itself.
Thanks to Mark VK5QI for his assistance is getting me up and running.
I've been playing around with APRS again and notices some new(ish) software called PinPoint. It is a windows based package that is very tidy in appearance and easy to setup. It will even act as an iGate! I haven't heard of anyone using it in VK but thought it was worth a try, so try I did. It all seemed to work well but it reported the beacon from my TH-D72 incorrectly, placing my position north by almost a degree. (And when you live in Darwin this is even more noticeable.)
After going through all the possibilities I came to the conclusion that there was a bug in the software, and given that it was developed (and in use) in the northern hemisphere without issue, I surmised that it may only be a problem that shows itself south of the equator. Therefore I decided to write to the developer, Frank AB0WV.
After a couple of emails in which additional information was shared, I received the following reply: -
Hi Mal,
Nice work! Your instinct was correct. This only happens on the southern hemisphere. I convert the raw latitude data into the desired display format in the code (degrees & decimal minutes, degrees, minutes and seconds, etc) and was not bringing the negative sign (for southern hemisphere latitude) across in my conversion for the fractional part (the section after the whole degrees), so, the fractional part was subtracted from (rather than added to) the whole degrees after the conversion of degrees, and the fractional part separately. Hope that makes sense. Once I added that in, it worked fine.
Nice find! Thank you!
A fix has been made and is now available on his site.
There are a lot of very generous hams like Frank around that share their efforts (software etc) with us and it's great to have assisted in some small way.
On this current road trip I'm running APRS on 30m using my IC-705 and an Open Tracker OT2m made by Argent Data Systems. The OT2m has been sitting in a cupboard for a few years, so good to get it out and dust it off.
Coverage has been patchy but it's not bad for running a max of 10 watts.
I've also been running 2m APRS on the Satellite frequency of 145.825MHz. So far I have managed one beacon reaching a SatGate in Depasar.
The following is just an update on Joel’s setup (as used on his NT to QLD trip).
An IC-705 was used for 30m, this was set to10w (Max) and connected to a mono-band whip. Modulation came from a Windows XP laptop running APRSIS32 with the U7ZHO sound modem.
A Yaesu FT-891 was used for 40m, set at 50w and connected to a separate mono-band whip on the car, this time using a raspberry pi, with Direwolf and Xastir.
An FTM-400, set to 10w and feeding a normal dual band vehicle whip, was used for the Satellite beaconing.
Given the minimal 10w on the 30m band (compared to the 50w on the 40m band), I would say that 30 metres is still the preferred band for this sort of activity (that is, if this band is available to you).
Joel obviously shares his affection between Icom and Yaesu, and also Windows and Linux! Good on you Joel!
I’ve been interested in APRS from the early days, even before the proliferation iGates with the shift from dial-up to dedicated 24/7 internet connections. I’ve run APRS in my car on both 2m and 30m whilst traveling and even sent the occasional APRS out on the 2m Satellite frequency. I have memories of being on the Nullarbor and reaching an iGate in Perth via the ISS (this on 2m), as well as having my 30m beacon being iGated by a station in Italy. It’s all a lot of fun but it’s not for everyone!
Over the last couple of years, I’ve become friends with Joel VK8JG who shares my interest in APRS and has been living in Darwin. Friday was his last day here before relocating south. (Anywhere else in Australia is referred to as ‘south’ when you live in Darwin!) For this trip south Joel managed to set his car and caravan up with four separate APRS transmitters, one of 2m Terrestrial (145.175MHz) VK8JG-8, one on 2m Satellite, (145.825MHz) VK8JG-9, one on the 40m HF band (7.0452 Mhz), VK8JG-15 and one on the 30m HF band (10.1476 Mhz USB) , VK8JG-14.
It’s interesting to compare these side by side as Joel drives to Brisbane. I have included screenshots of the Satellite, 40m and the 30m Beacons below (you can click on the image to in-large them). From memory, the 30m beacon is only 10watts. (I’ll need to check this, and the output power on the other bands.)
The Satellite APRS is fascinating. Joel has consistently beaconed through the ISS and also once through LAPAN A2 (IO-86). The latter is understandable as LAPAN A2 is in an equatorial orbit, and its coverage of Australia is limited to the norther reaches. Joel has been heard by YD8VMS-6 and YB8VRA-4 in Ambon, Indonesia, via the ISS and IO-86. VK8JG-9 to YD8VMS-6 was at a point-to-point distance of just under 2000km. Even more impressive are the beacons into VK5ATN-3, at just over 2000km. Joel’s beacons have been iGated 16 time during six passes in just under 48 hours.
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| 2m Satellite - VK8JG-9 |
The 30m and 40m Beacons provide a good side-by-side comparison, although we must consider the difference in power between the two. (Again, I will need to check the power output on 40m). Nonetheless 30m seems to be more consistent, especially during daylight hours. 40m seemed better in the far north in the early evening and into the night but there are large gaps in reception during daylight hours. As Joel moved south and closer to the iGates the reception improved and there appears to be a more consistent pattern emerging.
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| 40m - VK8JG-15 |
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| 30m - VK8JG-14 |
A second point of consideration are the number and location of iGates on each band. Joel’s 40m beacons were received by 5 stations located in VK2 (x3), VK6 and VK7, whist his 30m beacons were received by only two stations, one in VK5 and the other in VK4. There are, no doubt, a lot more iGates on both bands in operation. In the past 30m was the preferred band but in light of the Standard Licence not having access to this band I suspect that 40m may end up with more uses and therefore more iGates. This may already be the case.
In conclusion, it is my opinion that 30m is still the best band for HF APRS, it provides a more consistent path to iGates, this especially during the daylight hours. 40m seems to come into its own from just before sunset and through to mid-morning and may be better than 30m in the far-north during these hours. For large pasts of Australia, that are less remote, 40m may proof to be just fine, especially if the number of iGates on this band continues to grow.
If you are planning a road trip into the great beyond (obviously not into or out of VK6), and you have HF in your car, why not give HF APRS a go. And if you only have 2m FM why not add APRS into the mix and set it on the Satellite frequency of 145.825MHz. If you do, it will keep me entertained for hours!
Cheers for now!
Chris and I received our third set of Territory Passes ($200 each) last week and decided to head east. We drove to Kakadu (about 250km), booked in for two nights at Jabiru and did a scenic flight this morning.
This is the best way to see Jim Jim Falls, along with other waterfalls and spectacular scenery.
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| Chris and I on Middleton Beach. |
