Softrock works!
[ 1 Comment ] Posted on 08.27.09 in Amateur Radio, Home Brew, SoftRock, Uncategorized
It works!
Below is the build, essentially done. I need to better connect audio in and out. And I need to consider if I will add the DB9 serial connector. Marvel at the beauty of the Softrock TXRX V6.3 below.
And did I mention, it works!? Below I have it operating on the 40M band – tuned to W1AW at 7047.5 kHz. The software is Rocky. Rocky has a nice “auto IQ Balance” function which I had a bit of trouble getting to work nicely with an EMU 0202 USB sound card. I had the input volumes turned up quite high which seems to be a mistake. I tuned them way down and the software corrected itself very fast after that. I have absolutely no mirror images that I can see at all. Any images would have to be down at least 50-60 dB for me not to notice them.
The inbuilt sound card in my Macbook Pro does a pretty good job as well, but the EMU 0202 is an improvement. I’ll have to take some screen shots and compare them more systematically.
I did get a chance to transmit as well. I found I could get rid of the mirror images easily with the TX IQ Balance in Rocky. The mirror image was down at least 50 db after balancing. I have no idea what power output I have. I need to work on this a little more.
Problems and Concerns:
- The EMU 0202 sound card can sample at 192 kHz, but Rocky can not work at this frequency. Annoying!
- I suck at construction. I keep getting worn joints with the audio in/out and I’m wearing out the sockets.
- I really wanted to get this to work with my ASUS 901H Netbook, but it is really too slow to work at high sampling bandwidth. Also, the standard soundcard inside the netbook is terrible. Resorting to the EMU 0202 works, but sound out is choppy at times.
- The Local Oscillator Frequency is quite strong and radiates as well. I will measure just how much is radiated compared to a CW signal and it’s mirror image, soon.
In all, I’m very happy to have this project working. It is a bit ugly in places – I need to develop of construction skills a bit – but it has been a lot of fun. I should have it cased up soon and be ready to put into operation in the field soon. I should be upgrading to general license soon too (maybe extra as well) so I will be able to use this radio alone legally soon too.
SoftRock RXTX V6.3 Buiding
[ No Comments ] Posted on 07.17.09 in Amateur Radio, Home Brew, SoftRock, Soldering
I have been slowly building a SoftRock transceiver, which as it turns out is a bigger project than I thought it would be. Having said that, it has been great fun.
The Softrock family of kits are all centered around the SiLabs SI570 chip, a programmable oscillator, that is clocked at 4 times the center frequency required in order to generate I and Q (90 degree phase shifted) signals for mixing with received rf and passing onto a computer which acts as a software designed radio. This is of course the latest and greatest thing in radio and the SoftRock Kits are exploiting this technology cheaply and making it available to the hobbyist to build themselves. If you want to know more, check out the SoftRock page or read up on Software Defined Radio.
Only problem is the soldering of the chip!!! Check out the image below.
That’s right, surface mount is the go here, but not only surface mount, it is pinless! The chi is pinless!!! I have never done this before, but I have so far managed to solder the sucker in place and once under the command of a pic chip that programs its frequency in, it oscillates quite nicely (at 4 times the needed frequency).
The kit I am working on has a transmitter stage too, so it is a full transceiver. I will post more on it as I build more. I just wanted to show off my soldering of a pinless IC. Still can’t believe it works.