Malcolm,
I have both red shifted and blue shifted signals :-)
On this particular spectrum, the 21cm line is pretty broad, spread across almost 500kHz BW, indicating velocities between ~60mh/s receeding and ~20km/s aproaching.
I am wandering now why on Earth I didn't start this or similar project earlier.. beinng RF design engineer
Probably because I had too much electronics as part of my everyday work..
Also, vintage (but GOOD) equipment is much more affordable these days..
HP8922 that I am using as time base and IBASIC controller was US$25k 20years ago.. and I've got it for $100 on internal auction in the company I worked for. Noone wanted it because it was too heavy and too specialised (GSM testset).. so I said to myself, what the heck... another box in my cubboard won't be a problem, and it may be used for soemthing one day
