![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJBDnuEhS9gOIequGHCBs_iq5kjMYuSlXp2BzeD_L58rMV7l-KgdJ-ZnSDhlXdo6k-tZW7wNHbMKYnQdI2WzPGNUS3Gz7YkQjSyh0nDreAaP7cPSafkRe8IbbG7nTsJYFGtJq6E97S7zw/w289-h400/20200527_205859.jpg) |
Minor assembly required.
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![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjou0cXme3kUz-iDcZxDcJ-wD1l2cXNbk74JTlyf7U5VaRoebhi3ZVcnr97jLUH5riVfgElCuMxZcjWmGq8dcY-Gdqfez19TmEPyR7nMPhW35Kum0JekfIuoknruHA-MOanjXn9NRwRbgc/s640/20200612_092554.jpg) |
Hooked up to power, antenna, and ethernet for interface to PC. |
The
Hermes-Lite 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
radio.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijg52VEb3_eKS4YKdIxJzhIw1rV8rSWDopQWjg3LCddl_p8RDakPSxCEDYjv-xFzTvWSdne0uePcoIOQppOyohWBzIFuhIjdfwM6ogyr2YMJMI52fuTLfDIekHz439f8gs4FfFkW8_1tc/s640/Screenshot+from+2020-06-07+15-48-07-cropped.png) |
| SparkSDR
- 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. |
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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:
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggW8CpwAjnQGpBvphwL2yKrg7ehbDP6nafJlwGL0Y4SYfpsq453KNUX_eJ_eL4qrixI2ukJvsFLeVUj-_BOYUkqE7YTMtPAtJym-qkTlVO8L6VmMdEOObdNsYdKXaISxLdmvpXmb_3Zlc/s640/Screenshot+from+2020-06-15+02-13-30.png) |
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.
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On Raspberry Pi 4:
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGFwKHLFXxY9hhtrICCOTymxTS0CcVopcIyy9jG3dGBK_PXYITyfBdwzMk7U4aUwHyDKnKhrbZdeGsF8EqUeusCdMN5xI0bbB2URWD1nKX6srgT_BLkAmT5sQZd3Dny_ZtSoK-KzMtmcE/w640-h360/useforraspi4_2.png) |
VNC into Raspberry Pi 4 with about 16 receivers (SparkSDR). Sampling bandwidth 96 kHz. 26 Mbit/s going between HL2 and RPi4.
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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.