I built a step attenuator, highlighted in 2 previous posts, and quite some time ago I experimented with the AD8307 logarithmic amplifier chip and have a couple of prototype circuits for measuring low power signals sitting around in the junk box. I have the prototype SigGen as well the Arduino board I used for those experiments was still in one piece with the original program. So, why not put all the pieces together and see what happens.
A quick assembly of the various boards and run through shows some promise but its obvious some work to optimize the code will be necessary. Another issue that has become a bit obvious is how to assemble all this in under one box.
The SigGen uses a Nano and I'm wondering if I can fit the code for the 8307 into that program and that way I can eliminate an Arduino. Space is tight in the Nano but the 8307 code is not huge. Time will tell.
From left to right, the SigGen, Step Attenuator, AD8307 board, and the Arduino running the RF measurement program.
Peter
ReplyDeleteShouldn't be much problem have everything being controlled with a single Nano. Using the step attenuator you can easily find a value for counts/dB to make power readings fairly easy,just need one known value to get the dB offset. I would probbly put a switched 40dB attenuator before the step attenuator to get abound a 100 dB rnge. Since the noise floor on all the 8307 projects I built is around 72 dBm. I would put the 8307 meeasuring poinT between the tWo step attenuators. Getting down to around -100dBm will require some good layout and shielding. Too bad we wont meet at FDIM this year.
DuWayne KV4QB
At the moment there is 2 Nanos and 1 Duemilanove. SigGen, Attenuator and the 8307. Good enough while testing. Going forward I think I have 2 choices. Put the 8307 code in the SigGen Nano or in the Attenuator Nano. Not enough space to combine everything into one Nano.
ReplyDeleteInteresting suggestions that I've not thought about. More noodling to do yet.
When I have a project that has several modules wired together, I have a board with a LEGO surface glued to it. Then I just use a few bricks to make walls to hold each module in place. Advantages are that the "Lego-board" circuit can be easily moved as a unit. And, with the plastic surface, no worry about laying exposed circuit boards on some metal scrap.
ReplyDeleteInteresting idea. Not to worried about shorts, but with the modules connected in 2 places via various fittings, the height differences between the boards puts a strain on those connections. Lego seems to be a solution to take that into account. And make use of the 1000+ pieces stashed away since the boys moved out years ago. hihi.
Delete