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SOTA spotting over HF with your Android cell phone

Hi Everyone,

There is a group of software developers (http://www.dxsoft.com) who have produced a Weather Android app, but also included custom APRS functionality into it as per my request. This means you technically should be able to spot yourself over HF APRS where there is no cell reception or line of sight APRS digi-repeater available.

Currently, I can spot myself over 40m band with JS8CALL, but it requires a laptop to be carried to summits. I would rather prefer to use my cell phone instead and most of us carry it anyway. To me this is a great step of improvement to reduce weight.

I do not have Android cell phone unfortunately. Therefore, I am asking for those who have Android cell phone and available to be able to test this app to see if you are able to spot yourself and post your results here. If not mistaken, you would be the first one to achieve HF spotting from a cell phone!

You may find the same software on the bottom left corner of this page: The program for short text messages exchanging over HF radio.

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Direct link to the software: https://www.dxsoft.com/hfpgateng.apk (Android only). They are developing iOS as well.

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Cheers!
73
Gokhan
VA6GOK

2 Likes

Hi Gokhan,

I am curious…
Could you explain how this would be used?
A gateway - as the name suggests - would be at a base station at home I guess and pickup APRS at the HF APRS typical 300 baud ? But that’s not the intention I guess?

So the Android phone would need to generate an AFSK audio signal that can be fed into the microphone, line in or via an OTG-USB cable using a modern radio (soundcard mode).

Maybe you can explain the normal usecase(s) of this app?

73 Joe

2 Likes

Hi Joe,

I am sorry, I am not able to fill you in on most of your questions as I do not have Android phone and therefore, haven’t tested this software in its main purpose normal use. However, what I would do, I will forward your message to the developer and ask him. When he replies back to me, I will posted it.

The intention would be connecting your cell phone mic/speaker via cable or Bluetooth (ICOM 705 may work) to your HF radio and send out APRS audio signal through an HF band to spot yourself without relaying on SMS or line of sight digi-repeater, but still will be using APRS through HF.

73
Gokhan

3 Likes

This is the response I received for your questions:
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Thanks for the info.
Just for me to understand. Would it be difficult to generate APSR AFSK on the phone? I think APRSdroid does that but only at 1200 and 9600 baud.
As far as I know there are 300 baud HF gateways already out there.

It feels like an additional layer of dependency with the extra protocol and proprietary software for this gateway? Maybe the RBN skimmers (that are already all over the globe) could monitor also for HF APRS packets (or even a “new” or existing protocoll for messaging)?

But maybe I don’t see the full picture yet.

73 Joe

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Hi Joe,

I haven’t invested enough time to answer your questions unfortunately. and I use iOS and can’t make comment on APRSdroid, but I do know that I can send APRS messages from Linux based JS8Call and spot myself.

I posted your question, this is the response received:

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Dieter is talking about HFPager sofware in this last message.

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Okay thanks for the clarification. I am aware of the JS8CALL to APRS bridge and if that would work on a phone that would be great.

I am not familiar with the PS-18 protocoll. 5 baud is indeed very slow. I can have a lunch break while the spot goes out hi

Any info how many of those gateways are operational / or are planned to be online?

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300baud FSK is a terrible way to send data on HF. It has a very low effective throughput with the retries etc. The packets are too long for something with no FEC. That’s why things like robust packet etc. appeared to replace it.

If this is what I expect then it may be 5baud but there are probably plenty of bits per symbols so 5baud != 5bps.

EDIT Ah, so I come back from a phone call and post the reply only to find it’s 4 bits per symbol with FEC

2 Likes

Once approved, Dieter (from HF Pager) is joining to the forum to reply some of your questions and I will learn from everyone!

Thanks,
73
Gokhan

3 Likes

Sounds indeed interesting if enough awareness is generated to motivate people to have gateways up and running 24/7.
Any chance to get is working with RTL-SDR dongles or Kiwi-SDR or similar RX options? Or is a reply (TX) by the gateway needed for the protocoll to work?
If you can have the gateway as a linux service on a Raspberry Pi and connect a SDR dongle then I can setup something in my brothers garden :slight_smile:

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Hi everyone,
I am using HFpager in a group of German and Austrian Hams for some time now and we have close contact to the developers Sergej UA9OV and Evgeny UA3AHM. Here is a short introduction of the concept:

https://nvis.club/en/articles/using-your-smartphone-on-shortwave

It is based on an article in the German cq-DL magazine. This article does not reflect yet the new capabilities of the gateway and the weather server concerning APRS text, as it is older. But it gives an introduction and explains what has to be done to use HFpager “on the mountain”.

I myself use an Elecraft K2, a uSDX transceiver and Phaser 60 and Phaser 80 data transceivers in the field, often from mountain (maybe only hill?) tops but I haven’t made it SOTA events so far for some reason, but I am aware of SOTA and do like the concept very much.

I’ll be glad to give any assistance.

vy 73 de Dieter DL1DBY

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