Blind beamforming uses Singular Value Decomposition to form beams automatically that separate multiple overlapping signals. This sounds like a good idea for the HF bands. The link goes to one paper, there's a lot more, almost all of it over my head mathematically.
I'm in the process of playing with some simulation code.
K1LT sent me some DVD of data streams captured from his
4 antenna linear array for 160M. The initial results seem promising, but more development requires my own multiantenna array.
I designed a variant of the Softrock Ensemble II receiver with 4 channels using
Eagle schematic and board layout tools and upload the results regularly to my Subversion repository.
- http://www.wa1hco.net/Rx_HF_Multichannel/
Here's links to .pdf files
The /trunk/ directory contains the results of debugging and will be the V2 design if it gets built. The /branches/V1/ directory contain the exact files that went into the circuit card fab.
Current status is that the USB interface and Si570 control appears to work under usbsoftrock software. Quisk recognizes the card, but tuning doesn't resulting changing frequencies. I'm just starting the process of debugging the RF signal flow, QSD mixer and analog amplifier.
This image of the finished four channel HF receiver comes from a scanner. They have good depth of field and maintain good focus ever with significant component height. The original image was scanned at 600 dpi. I don't know what blogspot will do to it.