APRSIS32 sends ACK twice


Demetre - M0SUY/SV1UY
 

Hi, does anyone know why APRSIS32 sends ACK twice?

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73 de Demetre M0SUY/SV1UY
APRS: 1st & best Social Network


Lynn Deffenbaugh
 

Because a messaging spec somewhere recommends that the ack be sent on RF twice in quick succession to improve chances of reception.  It's not mentioned in the APRSISCE retries page, but that is also a good read:

http://aprsisce.wikidot.com/message-retries

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 3/24/2022 4:32 PM, Demetre - M0SUY/SV1UY wrote:
Hi, does anyone know why APRSIS32 sends ACK twice?


Demetre - M0SUY/SV1UY
 

Hi Lynn,

Thanks for the reply.

I would like to use APRSIS32 with VARA because your APRS Program is by far the best of all APRS Programs, but since VARA does not support CSMA like PACKET RADIO or ROBUST PACKET RADIO, is it possible in some future version of APRSIS32 to be able to setup in the XML configuration file the following as options?

1) the possibility to adjust how many ACKS to send per received frame (i.e. single or double),
2) also to be able to adjust how many APRS TEXT MESSAGE RETRIES you want the program to use,
3) to be able to adjust how many seconds are allowed between each RETRY
4) is it possible to include some sort of BUSY Detector on VARA Traffic included in your program would be great since the VARA Modem does not have a BUSY Detector and it relies on the External program using the VARA Modem unfortunately.

Of course all these should have the default timing unless someone wants to alter them.

I believe this will benefit HF AX25 APRS and HF ROBUST PACKET APRS too because the current algorithm works great VHF PACKET APRS but for HF I feel it is too aggressive!

--
73 de Demetre M0SUY/SV1UY
APRS: 1st & best Social Network


Lynn Deffenbaugh
 

Those are all reasonable configuration except number 4.  APRSIS32 relies exclusively on the TNC/Audio/RF interface to handle all of the link-level stuff.  It assumes that a packet can be queued to send at any time and the interface will handle whatever is necessary to ensure a clear channel.

Take #6 up with the VARA Modem folks or see if someone can write a piece of shim-ware to go between APRSIS32 and the Modem itself.

Besides, if the Modem doesn't have a BUSY detector, how would an external program even begin to come up with one?

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 3/29/2022 2:48 PM, Demetre - M0SUY/SV1UY wrote:
Hi Lynn,

Thanks for the reply.

I would like to use APRSIS32 with VARA because your APRS Program is by far the best of all APRS Programs, but since VARA does not support CSMA like PACKET RADIO or ROBUST PACKET RADIO, is it possible in some future version of APRSIS32 to be able to setup in the XML configuration file the following as options?

1) the possibility to adjust how many ACKS to send per received frame (i.e. single or double),
2) also to be able to adjust how many APRS TEXT MESSAGE RETRIES you want the program to use,
3) to be able to adjust how many seconds are allowed between each RETRY
4) is it possible to include some sort of BUSY Detector on VARA Traffic included in your program would be great since the VARA Modem does not have a BUSY Detector and it relies on the External program using the VARA Modem unfortunately.

Of course all these should have the default timing unless someone wants to alter them.

I believe this will benefit HF AX25 APRS and HF ROBUST PACKET APRS too because the current algorithm works great VHF PACKET APRS but for HF I feel it is too aggressive!


Demetre - M0SUY/SV1UY
 

Thanks again for reply Lynn,

I do agree with you for number 4 but I have tried and maybe I could not make the VARA author understand due to language differences.

I would be glad if you could implement my first 3 questions because they will improve HF APRS a lot. I am on 10147.30 kHz USB DIAL every day using 2 sessions of APRSIS32, one as M0SUY-10 for 300baud PACKET APRS and another as M0SUY-11 for 200baud ROBUST PACKET APRS using one HF Radio! I also run another session of APRSIS32 on 144,800 kHz for 1200baud PACKET APRS and I am very happy with your program.

--
73 de Demetre M0SUY/SV1UY
APRS: 1st & best Social Network