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QPSK63?


"g4ilo" <julian@...>
 

Hi to Chris and the group. Thanks Chris for making a very interesting program. I am one of the people who can't make full use of it yet as I am not using the "default sound card" with my radio. I have plugged one of my QRP rigs in to the mic socket on the computer just to see what I could get, and have received some corrupt packets from DL8RCB-10 and a couple of beacons from OZ1BZJ.

There is probably a good reason for this, but I wondered why PSK63 was chosen instead of QPSK63? From what I read about this, QPSK63 contains some forward error correction which would improve reliability and reduce the number of dud packets.

Just seem to have copied a good packet from DL8RCB-10:
DL8RCB-10>APSK63::G4HYG-2 :GUTEN MORGEN Chris!{5

Don't know if this was sent to the APRS-IS server or not.

One more question: What happens if someone spots my call G4ILO-15 and sends a message to me that comes via the Internet? I tried sending a message to myself using Lynn's client on my phone and it appeared briefly in the APRS-IS Server data and was eventually lost.

I would support all the suggestions Lynn has made. If APRS Messenger could be used as a TNC by Lynn's client then this would be really interesting and useful as APRS on VHF here is a dead loss.

Julian, G4ILO


"g4hyg" <chrism@...>
 

Hi Julian,

Good to see you've joined us on the forum.

I'll see if I can add the soundcard option to the program tonight. If not it will be later in the week.

Most of the signals you will see on HF are being sent to the APRS-IS by igates at G4HYG-2 and OZ1BZJ. More igates will also act as diversity receivers increasing the probability of packets sent to the APRS-IS.

I chose PSK-63 for three reasons:

I tested QPSK-63 and there is some improvement but not enough to overcome the other two reasons.

Users of QPSK-63 have to be using the same sideband USB or LSB. PSK-63 can use either.

It should be possible to make a "simple" PSK-63 tracker unit using a PIC microcontroller. QPSK-63 would probably be too complex to run on a microcontroller.

At the moment the current version of APRS Messenger is as far as I have got. In the very near future I want to add GPS tracking for HF mobile use, a TCP port to connect to Lynn's program and add a routine to extract messages from the internet addressed to the user.

I understand your situation away from the APRS VHF network only too well. I worked away from home some years ago and the only way I could get an APRS signal out was by HF or the ISS!

73,

Chris, G4HYG


"g4ilo" <julian@...>
 

Hi Chris.

FB on why PSK63 is used.

I will look out for the new version as I am keen to try on transmit.

It would be interesting to know what power people are using, and to read some comments on the performance of PSK63 from people who have had experience of using APRS on HF with 300baud packet.

73,

Julian, G4ILO

--- In cross_country_wireless@..., "g4hyg" <chrism@...> wrote:

Hi Julian,

Good to see you've joined us on the forum.

I'll see if I can add the soundcard option to the program tonight. If not it will be later in the week.

Most of the signals you will see on HF are being sent to the APRS-IS by igates at G4HYG-2 and OZ1BZJ. More igates will also act as diversity receivers increasing the probability of packets sent to the APRS-IS.

I chose PSK-63 for three reasons:

I tested QPSK-63 and there is some improvement but not enough to overcome the other two reasons.

Users of QPSK-63 have to be using the same sideband USB or LSB. PSK-63 can use either.

It should be possible to make a "simple" PSK-63 tracker unit using a PIC microcontroller. QPSK-63 would probably be too complex to run on a microcontroller.

At the moment the current version of APRS Messenger is as far as I have got. In the very near future I want to add GPS tracking for HF mobile use, a TCP port to connect to Lynn's program and add a routine to extract messages from the internet addressed to the user.

I understand your situation away from the APRS VHF network only too well. I worked away from home some years ago and the only way I could get an APRS signal out was by HF or the ISS!

73,

Chris, G4HYG