Building a LoRa APRS 439Mhz iGate (Part 1)

Even lighter light aircraft than I was expecting! Cool! :small_airplane:

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My iGate has reported a few packets coming from more than 80km away

It seems to pick my tracker up consistently on one particular corner of the A4117 at Foxwood in Shropshire (just to the East of Titterstone Clee). Thatā€™s about 80km I think!

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This morning Iā€™ve seen a lot of packets like this:

  Aug  1 06:58:18 M0LEP-10 CA2RXU_LoRa_iGate_1.3 RX / GPS / M0JKS-1 / APLRG1 / WIDE1-1 / -127dBm / -14.50dB / 2761Hz / 53.44967N / -1.86750E / 199.1km / Peak District APRS LoRa Digirepeater (439.9125MHz, 125KHz, SF12)

Reported range is interesting, but it seems the device at the other end may have fallen into a rather rapid fix-transmitting loop, as they were for a while arriving at the rate of one packet every ten to fifteen seconds. Any ideas?

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Looking at the raw packets from Daveā€™s digi, it started misbehaving at just after 7am this morning - sending its beacons twice per minute, rather than twice per hour.
We had some electrical storms overnight, so it may have been disrupted by them. But I spoke with Dave yesterday and he said that the local sheep had found his remote installation and been nibbling at it - so it may be a case of ā€œovineā€ intervention"?
Anyway, youā€™re the most distant station to have picked it up so far, thanks to some early-morning tropo propagation:
image

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Almost 200km on 70cms at more-or-less ground level(-ish) isnā€™t bad. I tracked a high-altitude balloon putting out 10mW of RTTY on 70cms at over 500kms once, but it had something over 30kms of altitude to help itā€¦

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Happily, it reverted to twice-hourly beacons just before 9am:


Iā€™ve already mentioned to Dave that the beacon text is overly-verbose and that thereā€™s a spurious ā€œechoā€ a few seconds after each.

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Looking further back in the Raw Packet archive, it showed exactly the same problem on Wednesday morning, between 6 & 7am - so we can rule out last nightā€™s thunderstorm.
Maybe itā€™s due to the battery voltage varying with temperature and solar panel input (or perhaps itā€™s just around the time those sheep have their breakfast?)

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I have messaged Dave in case heā€™s not aware.

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Noted. Investigating

Dave

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A low battery could cause it to power down, then once itā€™s charged up slightly come back on and send another beacon.
With the recent good weather there should be plenty of charge in the batteries though.

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Does anyone know whether ā€œUnattendedā€ operation is permitted in France under CEPT Recommendation T/R 61-0 ? I have a friend who would owns a property in France and, since Brexit can only visit for 90 days in a 180 day period. When he is ā€œallowedā€ to visit he would like to run a LoRA APRS iGates for the duration of his stay ā€¦ and so asked me whether he could do so using his U.K callsign (e.g. F/G4XYZ-10). Licensing issues aside, I think the other obstacle could probably come from restrictions in the AX25 protocol. As I understand it, it looks like only alpha numeric ASCII characters are allowed in the callsign, but does this apply to ā€œspecialā€ characters (for example ā€œ/ā€) ?

Dave

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For APRS on handheld radios using GPS there is no need to change the callsign when visiting another (CEPT) country as long as you are permitted to transmit on that band/mode.

By broadcasting your position you show where you are. So it would be redundant information.

But I have no clue about unattended operation.

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If he owns a property then why doesnā€™t he get a HAREC certificate from Ofcom and apply for and obtain a French licence. Then he can use his French call and problems with callsigns goes away.

If I owned French property Iā€™d be applying for a Visa so I didnā€™t have to faff about limiting stays to <90 days per 180 day period.

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Thanks Joeā€¦ I guess configuring.the iGate as RX only and disable the beacon means itā€™s not ā€œunattendedā€ (.i.e. doesnā€™t transmit).

Dave

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APRS.fi is filtered packets that are clearly a modification of the original packet received.

APRS rules state that no modification of a packet should be performed by an iGate

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Thanks for that clarification Ricardo.

This IGate project was developed by IoT4Pi (in Austria) a few years ago, and when I first built mine and tested it in April and May 2024, there was no problem at that time with the appended SNR & RSSI values. However when I next came to use it in July, the filtering was clearly rejecting them.
I soon worked out how to modify the (Python) code to suppress the values and have forwarded my comments to the developers in Austria.

I found it a very nice project, as I already had a spare Raspberry Pi2B and an Ra-02 LoRa board, so it cost me nothing to put together!

73 de Ross

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is there code available to see about a few topics of packet processing?

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Iā€™ve just spotted that SP0LNDā€™s High-Altitude Balloon is flying over Scotland (at around 12km altitude) with a LoRa tracker on 439MHz, so the Northerly IGates could pick up some unexpected distances today:


Iā€™ve set my IGate up with the antenna pointing N, just in caseā€¦

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Tracking aprs.fi ā€“ live APRS map

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I wonder why your screenshot doesnā€™t show all of the i-gates?

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