AmateurRadio.com

If you have been following my attempts to set up beacon monitoring using a software defined radio (SDR) then you may remember that I had found that Omni-Rig, the radio control software used by Faros, the beacon monitoring software, would not talk to the virtual serial port created using VSPE in order to control the SDR-Radio software. I thought there was a problem with SDR-Radio’s emulation of the Kenwood control protocol. In fact, that turned out not to be the case at all.

A reader asked if I had tried DDUtil, a.k.a. VSP_Manager, a program by K5FR so I got hold of a copy. The instructions made my hair stand on end as it seemed very complicated. But I managed to set up a virtual port pair between COM8, the control port that SDR-Radio was using, and COM9 which would be used by Faros. VSP_Manager threw up a few error boxes but it still seemed to have done what I asked. I then tried setting up Omni-Rig. The first attempt failed, but I decided to try again as the help files actually showed VSP Manager being used with Omni-Rig and sure enough I had Faros changing bands and frequencies of SDR-Radio.

My joy was boundless, but not for long. I fell at the next hurdle which was using a Virtual Audio Cable (VAC) to pipe the audio from SDR-Radio into Faros. VAC also looked complicated to set up, but what I was attempting to do was the simplest application of it. I created a virtual audio port and set the SDR-Radio output to use it. As soon as I connected this to Faros’ input Faros began spitting out “divide by zero” message boxes so fast that I couldn’t close them quick enough to get back to the Settings window to change it back again. Another brick wall.

A separate issue was that of creating a serial port splitter to allow two applications to connect to physical port COM3 used by my Elecraft K3. VSPE could do that easily, but yesterday I discovered that WSPR would not talk to the virtual port created by VSPE. However, VSP_Manager does not seem to enable you to split a real port into a pair of virtual ones anyway, so I did not pursue this avenue any further.

If you are confused trying to follow all this you are not the only one! I have abandoned the idea of using an SDR for beacon monitoring and am breathing a sigh of relief that I never decided to go down the road of buying a Flex or other software defined transceiver. SDR will never catch on until connecting the software defined radio to logging programs or digimode software becomes as simple as plugging in a real cable.

When you measure the energy out of a GSM cell phone at the moment of initiating a call, you get the picture to the right. It shows the first 15 seconds.

For the first 3.5 seconds there is the signalling between the phone and the base station. Then the connection is established, but after some time (at 4.2, 5.6, 7.5 and 9.5 seconds) one can see how the phone turns the power down, according to the commands it gets from the base station.

The first example was for the case of a strong received signal, all bars are shown in the signal strength meter. The reduction in power, preservers battery life and as a side effect the user is exposed to a smaller amount of radiation. Interestingly, one can see that after a while there is a small adjustment of the power and it is turned up a bit (at 11.5 seconds).

In other cases one can see a situation which follows the same pattern in time, except that the power stays at a high value. This second recording was done in my basement where GSM coverage is much poorer. Here the phone’s signal level indicator hardly shows any signal.

The third plot is a zoom of the previous one. Here one can see how the phone only transmits 1/8 of the time as it shares the channel with 7 other phones in a time multiplex. It is allowed to transmit every 4.6 ms and this is the reason why one often can hear a buzzing sound at 1/4.6 ms = 217 Hz in equipment which is placed close to a phone.

One also sees another frame structure, as the phone transmits 25 bursts and then breaks for one burst before continuing. Every transmission consists of 150 bits, but that is not possible to resolve with the simple setup that was used here.

The equipment was a dipole antenna and a simple diode detector:

• A half wave dipole antenna for 950 MHz has a length of 0.5*3*10⁸/950*10⁶ = 15.8 cm, thus the antenna is about 2 x 8 cm (probably not very critical). The antenna was made from stiff self-supported wires.
• There is a resistor of R=1 kohm across the antenna and then a Shottky diode which acts as a detector (A Shottky diode which handles higher than 1 GHz is needed and BAT46 was used here), and finally a 1000 pF capacitor as a filter.

Sometimes it seems as if half the posts in this blog relate to trouble with computers.

After I got back from the hospital today I thought I would try some WSPR for a change. Paul PC4T had mentioned that conditions on 80m were good. 80 is not a band I often use so I thought I’d try there. But no sooner than I had tried to change band than the software beeped rudely at me. The console window contained an error message: serial_open: Unable to open COM13 – Invalid argument.

COM13 is a virtual serial port splitter on COM3 which I’d created using Eterlogic’s Virtual Serial Port Emulator, VSPE. I’ve used this utility for years to create virtual serial ports so that more than one program can open my radios’ computer control ports at the same time. I’d used one to try out CW Skimmer with KComm before Christmas. As I’d uninstalled Skimmer I removed the virtual serial port. WSPR, which does its rig control through hamlib, then opened COM3 up just fine.

That’s a temporary solution, but I haven’t given up the idea of running other ham software alongside KComm for good. I think there are other serial port splitters out there (there’s com0com which was far too complicated for me to figure out) but VSPE has always worked for me until now. Don’t you just love computers?

Last weekend I attended the Houston Vintage Radio Association holiday dinner & picked up a Philco Tropic Model 3012 during the fundraiser auction. I had let a few other radios go without placing a bid and was beginning to think I might go home empty handed when I saw the Philco “on the block”. A few seconds later I was the proud owner of this vintage receiver.

Philco Tropic 3012

Information on this model seems a little scarce, however the style of case was introduced by Philco in 1951 and used in their line of AM/FM receivers for many years after that. This particular example is a transformer-less AC/DC set with a potentially live chassis and the unusual (to me) lineup of 14Q7, 7B7, 14B6, 35A5 & 35Y4 vacuum tubes.

What prompted me to bid on this particular radio was the inclusion of two shortwave bands in addition to the typical AM broadcast band. The dials are marked off in meters which also appealed to the ham radio side of my interests.

After attaching a short length of wire as an antenna I was able to pick up signals across the two SW1 & SW2 bands so I’ll be interested to see what it can receive with a long wire antenna at night.

After a gentle cleaning with dilute mild detergent to remove dirt I rubbed in some beeswax polish to restore the original gloss. Sadly the plastic dial is cracked in the middle but I can look past that given its a little more unusual than the typical All American Five receiver.

Being over fifty years old I wonder what this radio has been used to listen to and what stories it could tell. Perhaps it gave some youngster his or her first taste of ham radio, listening to shortwave stations and AM QSOs until they received the final demand to, “Switch that radio off and GO TO BED!”

who was in the pot of water, that little by little got warmer and warmer until it was boiling.

I was sitting in the shack having a QSO with Greg KD5EW on 15 Meters when I turned around and took a good look at my surroundings. How did it get this bad? How did this part of the basement become such a mess?

Beginning during the weeknights after work, and continuing next weekend, I am determined to clean this space up and make it more functional again.

It will be interesting to see how many things I find that I forgot about and didn’t realize that I have.

73 de Larry W2LJ
QRP – When you care to send the very least!