The HP 8922 is an old, but very nice and versatile GSM Test Set. One interesting thing is that there are nearly no devices with the Encryption Option available for sale. Also you don't find a lot of information about this option in the HP Manuals.
I did some research (looking at the firmware) and it seems that the Encryption Option is not a piece of hardware but a special version of the firmware. A bit more detailed: The code of the GSM Channel Codec (it runs in an MC56K DSP) seem to miss the A5/1 encryption algorithm. The code for the DSPs (there are two main GSM DSPs, the other is for the Speech or BERT Codec) is stored in Flash memory. This memory can be easily removed from its socket, so it would be rather easy to enable the Encryption Option by copying the code from a unit which already has this Option.
If you have a HP 8922 with the Encryption Option, I would be happy to hear from you.
The Racal 6103G is another GSM Test Set. It is not that versatile as the HP 8922, but it is smaller and has more advanced features, especially interesting for me is the GPRS and EGPRS capability of this unit.
However there is one drawback: The Racal 6103G, at least the version which displays "AIME" in the main screen, cannot be used standalone as for example the similar 6103E. To use the 6103G, you need the PC Software (Windows) which controls the unit over GPIB. And no, the GPIB commands to control the 6103G are not similar to the GPIB commands of the 6103E, the 6103G uses a totally different and special binary-only command format.
You can buy the required PC software from the vendor, however it is very expensive (from more than 10000 EUR up to 30000 EUR, depending on the software options you need).
So be aware of this if you buy one of those units, they are sometime offered on eBay.
Something similar applies to a special version of the 6103E, it displays "Anite" in the main screen. I don't have one of those units, so I don't know the details, but most certainly you cannot use it standalone too.
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