Unexpected Ethernet activity with HL2

[David Taylor]

Running SparkSDR 2.0.932 with a new HermesLite 2. Using receive only, I see
data flowing /into/ the PC from the HL2, but also network data flowing /from/
the PC, likely to the HL2. With a decent buffer size, I had expected a small
outbound flow ("please send the next buffer") and a much larger inbound flow
("here's the next N kilobytes, get on with it").

As I know little about the HL2 protocols:

- am I doing something wrong with the program?

- why am I seeing transmit data (?) being sent even when receiving?

- is it possible to prevent this - e.g. by using the 10-receive firmware, as I
wish to minimise network load.

- is there a document describing the communication protocol [TCP/UDP, API etc.]?

Thanks,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-...@blueyonder.co.uk
Twitter: @gm8arv

[ahop...@googlemail.com]

Hi David,

this is expected, the command and control messages sent to the radio also contain the tx data so you need to send some to set vfo etc, by sending them at full rate the tx buffer is kept in a more stable state.  The tx is always 48Khz so it is generally less than the rx if you are using multiple receivers or higher bandwidths.  It is an interesting idea to reduce it for  receive only, unfortunately the gateware does not report that it is rx only(if my memory is correct) so I would have to play guessing games to disable it.

73 Alan M0NNB

[David Taylor]

On 19/03/2023 09:07, 'ahop...@googlemail.com' via SparkSDR wrote:
> Hi David,
> this is expected, the command and control messages sent to the radio also
> contain the tx data so you need to send some to set vfo etc, by sending them at
> full rate the tx buffer is kept in a more stable state.  The tx is always 48Khz
> so it is generally less than the rx if you are using multiple receivers or
> higher bandwidths.  It is an interesting idea to reduce it for  receive only,
> unfortunately the gateware does not report that it is rx only(if my memory is
> correct) so I would have to play guessing games to disable it.
> 73 Alan M0NNB

Thanks, Alan.

Stability is good, so I wouldn't suggest anything to disrupt that!

As a matter of interest, I compared the standard firmware with the 10 receiver
firmware looking at the network I/O at the controlling PC. I used receiving
20m FT8 as a test:

10 RX firmware: give 26.2 Mbit/s to PC, 13.1 Mbit/s from PC.
Standard firmware: 6.5 Mbps to PC, 3.3 Mbps from PC.

If 48 ksps the rate, and it's 2 x 16 bit samples per packet, that's 1.536 Mbps
giving approximately:

10 RX firmware: 17 streams to PC, 8 streams from PC.
Standard firmware: 4 streams to PC, 2 streams from PC.

Interesting!

73,