Saturday, January 8, 2011

RF over Fiber Optic

I have recently come across this idea. It's apparently possible to buy boxes that can convert RF signals into optical signals that can be sent over fiber and reconstructed on the other side with another box. There are converters for one way or transceiver purposes. Some have bandwidths of 2500mhz or even 4000mhz.

Here is a PDF with the basics.

Has anyone ever used something like this for Ham Radio purposes? I'm still looking around but it seems pretty obscure to me still. I'll make a new post if I find anything.

Monday, January 3, 2011

Tokyo Hy-Power HX-240 2m -> HF xverter

This is backwards from what you'd normally expect. You hook a 2m all-mode rig up to this and use it to receive and transmit HF. 2.5W/10W in on 2m translates to 30-40W out on HF. The going price is roughly $200. Neat.

Sunday, January 2, 2011


This is a handheld radio from a CB manufacturer, Magnum, that purports to do 10 meter and 12 meter all mode operation: AM/FM/SSB.

It's pretty shameful when a CB manufacturer does something that not even a ham radio one is doing. I know these are meant to be for freebanders but I kinda want one. I am normally 100% opposed to this sort of thing. They aren't fooling anyone when they sell the "10 meter amateur radios" on ebay that look and act exactly like a CB. If you ever bother to look up the manual for one, you see it's braindead easy to mod it for 11 meter use. They may as well put a switch on the front panel for crying out loud. I don't know if this handheld has a VFO mode or if it's more channelized junk. I haven't found out much information on it, besides lots of listings on stores that are primarily CB oriented. Some of them don't even pretend this is intended for amateurs who want a 10m or 12m HT, they list it strictly as a CB. It's a little pricey too, $210-$280 from what I've seen, and you have to mod it if you intend to switch bands from 10 to 12m.

Let's not pretend for a second that these are intended for amateurs though, these are meant for people who are going to "mod" them for CB use.

QAM modem IC?

While browsing some of the tapr HSMM information, including one of the message boards, I found a post referencing a very highly integrated modem IC for doing QAM data with an I/Q interface. Here is the post. and Here is the IC in question.

I'm going to quote from the webpage:
The CMX7163 QAM Modem is a low power half-duplex device supporting multiple channel spacings under host microcontroller (┬ÁC) control. Its Function Image™ (FI) is loaded to initialise the device and determine modulation types. 
The 7163FI-4.x supports 4-, 16- and 64-QAM modulations up to 96kbps in a 25kHz channel, with channel estimation and equalization to provide robust performance under realistic channel conditions. 
Flexible bit rates support a wide range of applications requiring a selectable bit rate and robustness.
 An integrated analogue interface supports 'direct connection' to zero IF I/Q radio transceivers with few external components; no external codecs are required.

The odd thing is the message board post quotes 64kbps in a 25khz channel but the chip maker's website says 96kbps. Obviously that'd be the 64QAM modulation. That's still very impressive, in my opinion. I'd love to see these incorporated into a design for a 440mhz or higher HSMM radio.

Just read the datasheet, you can do 96kbps with 64QAM, 64kbps with 16QAM and 32kbps with 4QAM. That is assuming 18,000 symbols/s (your baud rate). This falls well within the 19.6kilobaud limit on 2m but outside the bandwidth limit of 20khz. If you reduced the baud rate to 9000 symbols/s you'd take up half the bandwidth. It'd fit within the 56kilobaud/100khz limits in the 440 band just find though.

The downside is that these are only available in 64 pin packages, VQFN and LQFP. Small pins with little space inbetween but I've seen people who could solder it.

Return to Mt. Packet

KE9V has posted a list of basically New Years resolutions for ham radio and his #1 item is to set up a 1200 baud packet node again. I'd like to resolve to do the same. It's a shame that the old packet radio network(s) were tore down as the Internet got big. Even if packet was only 1200 baud, it's got reliability on it's side. Sure, the Internet's probably pretty resilient, but that doesn't include your connection to it. 1200 baud is super pokey but it's much faster than 0 baud. I would like to investigate HSMM installations but that will have to wait on personal funding and contingent on interest from other hams in the area, of which few have interest in computer technology I think.

Kenwood RC-D710 (D710) Control head... with other radios?!

I was clued into this on the Curling Smoke blog ran by KE9V. Here
As an aside, this links to a TAPR mailing list which is talking about the control head being on sale at HRO for $150. The posting was dated 12/25/10 but today (1/2/11) I can't find it on HRO's website.

Apparently the control head for the Kenwood D710 radios can be bought seperately because you can buy the radio without the APRS functions. The TNC and APRS logic are both in the control head so just buying the right one and adding it to the radio will let you add that functionality in. The interesting part comes Here. With the right cable, you can plug the head into any radio to decode APRS packets, even an HT! (Thanks to Bob, WB4APR for detailing this)

Apparently it's even still possible to connect the Kenwood AVMAP device to show the icons on a map.

Bob writes:
CONCLUSION: On long trips, no matter where you are, we hope you will see not only one of these recommended voice repeaters on your screen, but also the nearest IRLP or EchoLink node as well... This combined with APRS Voice Alert will guarantee that if there is someone nearby wanting to chat, we will find each other.

I've made the mistake of believing APRS is for tracking only in the past. I think it would be far more useful if people would use it to advertise local services, such as repeaters and echolink nodes.  Mr Bruninga really stresses this on his website and I really respect that.