SDR Selection

There are many SDRs on the market. In the table below you will find the main characteristics of the compatible “Remote SDR” models. This list will evolve in the future.

Nom	Band	RX	TX	Remarks	QSJ
RTL-SDR	30 MHz – 1,7GHz, Bandwidth 2 MHz	Yes	No	Dynamic 8 bits, The cheapest	40€
RTL-SDR	0.5 MHz – 1,7GHz* Bandwidth 2 MHz	Yes	No	Dynamic 8 bits, The cheapest	40€
HackRF One	1 MHz – 6 GHz, Bandwidth 2MHz	Yes	Yes	Dynamic 8 bits, Half Duplex	130€
Adalm Pluto	70 MHz – 6 GHz après modification, Bandwidth 1MHz	Yes	Yes	Dynamic 12 bits, Full Duplex, Poor frequency stability	200€
RSP1, RSP1A, MSI.SDR	10kHz – 2GHz	Yes	No	Dynamic 12 or 14 bits Interesting in HF bands	20€ to 130 €
SA818	144-146 MHz ou 430-440 MHz	Not used	Yes	NBFM only (1w)	10€

The SA818 found on the Chinese market is similar to an SDR. It does not exchange signals in complex I and Q form, but audio in analog form. It is programmed by a serial interface.

*RTL-SDR V3 – Frequency extension

There are now RTL-SDR V3 on the market that can work below 28MHz. Remote SDR (from version 4.5) is compatible with this new version. However, you should know that this is a degraded operation of these SDRs. There are 2 important impacts, namely:

• There is no longer any input gain setting to adjust the dynamics of the signals to be converted in the optimal 8-bit conversion zone. This can result in saturation on a strong signal.
• Input sampling is at 28.8MHz without filtering. There are spectrum aliases around 14.4 MHz. Thus a signal received at 7.074 MHz (FT8) will also be heard on 28.8- 7.074= 21.726 MHz. Similarly, a 20 MHz signal will be heard at 8.8 MHz.

This solution by its low cost is interesting to make ascan in the HF band (0.5 – 28 MHz) but does not constitute a performant solution.