PortableSDR 2.5 Debut!

Posted date: June 16, 2016in: NewsNo Comments

The PSDR 2.5 PCBs came back and look great (they are a little more orange than red though, what’s up with that?) As I explained in the video, I built up two, one with the STM32F4 that the PSDR2 uses, and one with the fire breathing STM32F7. I was able to get the F7 to work (and it doesn’t really cost more) so I’m going to include that chip in the design going forward.

I’d been deliberately vague about some of the new features I’d been testing in the recent test boards until I could see if they were going to work (I didn’t want to get everyone’s hopes up, you see) BUT! Since they seem to be working, here are some new things that your PSDRs will be able to do (keep in mind, the campaign was for a development radio and that’s still true, it’s not perfect):

Frequency coverage used to go up to about 37MHz. Now it can go from 80KHz to 175MHz, 183.5MHz to 236.67MHz, and 275MHz to 355MHz. So three more ham bands (6m, 2m, and 220MHz) FM broadcast band, aircraft band, and more are possible (no guarantees on the performance yet).
A digital variable low pass filter that can be switched in for receive, transmit, or bypassed. The idea here is to knock out the harmonics on the transmit signal before amplification. So far it seems to work, but there is a lot of testing left to do. (only works from 5MHz to 72MHz)
A small transmit amplifier. Should get us as high as 250mW. External low-pass filtering will still be required for transmitting a clean signal.
Reset and Bootloader buttons. The Bootloader button means you can easily put the PSDR into DFU mode which will allow loading new firmware over USB (details are still being hammered out, but it does work)
Higher quality GPS module (though I’m not sure about the new antenna)
Not one, but TWO LEDs!
Also, looks better, fits better, and is way easier to assemble.

There are only minor changes that I am going to make to the next board revision (to reflect the fixes I had to make) and then I should be ready to order! I am just not comfortable ordering the final boards without testing first, so I am going order PCBs and prototype one more time.