|Minor assembly required.|
|Hooked up to power, antenna, and ethernet for interface to PC.|
can listen on an unlimited number of virtual receivers which can concurrently monitor 4 bands at up to 384 kHz x 4 total bandwidth.
HF digital modes allow many simultaneous transmissions to fit into a relatively narrow slice of bandwidth.
The receiving capability of the Hermes-Lite coupled with specialized
software and the processing power of the computer allows for monitoring a
significant chunk of the HF digital mode frequency range using a single
- Transmitting on 20m with the built in 5W amplifier and N2ADR filter
board. Just over 20 virtual receivers monitoring HF digi modes with one
DigiU dedicated to JS8Call.|
It is somewhat intensive for the PC and LAN.
I was initially using a 2014-vintage i5 laptop which handled it but was a bit strained and the cooling fans were noisy in that state. Since then I have switched to a i5-3470 desktop machine which handles it better and with less noise. I am seeing about 2.5 TB/week (45 Mbit/sec) of data transfer between the HL2 and SparkSDR in the above receiver configuration with 192 kHz sampling bandwidth. The gigabit LAN has plenty of capacity left.
24/7 automated decoding of these signals contributes to an online reporting database allowing visualization of world-wide HF propagation activity:
|Pskreporter stats - HL2 with about 20 receivers over a 24 hour period. Each marker represents a station heard and color denotes the frequency (40m, 30m, 20m, or 17m). Transmissions between Alaska and Europe travel over the north pole.|
On Raspberry Pi 4:
|VNC into Raspberry Pi 4 with about 16 receivers (SparkSDR). Sampling bandwidth 96 kHz. 26 Mbit/s going between HL2 and RPi4.|
The Raspberry Pi 4 May be comfortably usable with up to about 4-6 receivers. Of note is the fact that VNC server uses a significant amount of CPU. I already disabled the "waterfall summary" for each virtual receiver with some CPU savings, but it seems driving the waterfall graphics adds a significant load especially over a remote connection.