Do I assume correctly that these provide a direct interface to the baseband DACs and ADCs? This could allow for many interesting applications, for instance when using TX1/RX1 in the RF domain while having two outputs in the kHz/lowerMHz domain for other stuff, eg TX2 I and Q, each of them as a separate output. And each of them is phase coherent to TX1 (of course, only to the baseband of TX1, not to the upconverted RF)
Question1: Did anyone ever use those XTRX baseband connectors?
And then question2: The upcoming Micro also has baseband connectors, and there is the announced LimeFEA HF, which interfaces to the RX baseband connectors. What is not yet fully clear to me: How are the micro baseband connectors routed? From the block diagram, I have the impression that the TX baseband connector interfaces to the LMS7002M, hence in the same way as for the XTRX. But for RX baseband, it is indicated that this connector interfaces to the LA9310. For the RX baseband, Micro is therefore different than XTRX, while the TX2 baseband routing is the same for both XTRX and Micro?
I can’t recall if we’ve used them in projects. @Zack might know.
We refer to LMS7002M as field-programmable RF (FPRF) and the reason for this is not just that it’s a single chip SDR, but because you can also power blocks up/down and access respective signals. So in the case of LimeSDR Micro we don’t use the integrated ADCs and DACs or digital signal processing, and instead interface with LA9310 via analogue I/Q. In this case LMS7002M provides blocks such as LO, mixer, analogue filter and LNA etc.
Alternatively you can do the opposite, use LMS7002M digital signal processing and ADCs and DACs, and integrate with external analogue circuitry.
With XTRX you can see ADC, DAC and GPIO signals on the baseband connectors:
Whereas with Micro it’s the LA9310 third and fourth receive channels (ADC) on X7:
X8 meanwhile is for analogue baseband input to LMS7002M second transmit channel.
It’s like this with Micro because LA9310 is 1T4R and LMS7002M is 2T2R. So by default, without any add-ons, you effectively get 1T2R (all via LMS7002M). With the HF add-on you get 1T3R, albeit not MIMO since the third ‘R’ is HF and a totally different analogue path.
Other possibilities might include e.g. creating a 4-channel oscilloscope add-on for Micro, using the I+Q inputs each of LA9310 receive channels 3+4 present on X7.