Friday, January 28, 2011

VHF propagation alerts over APRS

I have just set up an ANSRVR notification group (the APRS equivalent of an email reflector) called CDGVHF. The purpose of the group is to alert interested subscribers in the Cumbria, Dumfries and Galloway area to possible openings on the 6m, 4m, 2m and 70cm bands.

The APRS alerts make use of the email alert service of DX Sherlock which sends alerts of possible band openings customized to the subscriber's location, based on DX Cluster spots and other reverse beacon information. I have set up a subscription to send alerts of possible band openings workable from the IO84 grid locator to a special email address on the G4ILO's Shack web server. Using a feature of the cPanel web hosting, the email is "piped" to a script written by me in the PHP language. This extracts the subject header of the email which contains a succinct description of the alert, shortens it as much as possible and then sends it as a message to the CDGVHF ANSRVR group, which then forwards it to all interested subscribers.

Why is this better than just subscribing directly to receive the alert emails? Because I can now receive the alerts on my APRS-equipped hand-held, which should greatly reduce the chance of missing a good band opening because I wasn't in the shack at the right moment.

6 comments:

LY2SS said...

Great service, Julian. Albeit a bit late IMO in this era of ubiquitous cellphone/wifi networks... I mean who wants to carry additional weight in his pocket?)

Once I thought about Google calendar - they have free sms remainder. They have ability to insert events from linux shell too. Get alerts from Sherlock, crop them, push to gcalendar. Just a raw idea...

Julian said...

That's not a road I want to go down. I mean, I can do APRS on a cellphone (and with real maps.) I can talk to people on a cellphone (with EchoLink, or just Skype.) Who needs ham radio anyway?

LY2SS said...

Julian, please don't take my words/idea too seriously. Your aim was not to miss propagation when it comes. Then I thought that having cellphone in pocket (unavoidably these days), why not use it? We already use blog comments (not radios), wspr networks, rbns, dx clusters etc etc - all they use internet as a transport...
Should true ham have to be Luddite?

LY2SS said...

Actually my gsm operator was giving me opportunity to get DX Sherlock alerts for free to my phone (subscribed to alerts as a phone_number@operator.com) But about year ago they closed the service and I started to miss those SMSs. Even in the 3AM!

Best 73! Zilvinas

Julian said...

Yes, Zilvinas, I get your point. But actually I like to have my ham radio on a separate channel. I even have a separate email address for ham radio stuff. Because there are times when I want to switch off from the "real world" and the hassles that normal email and phone calls can bring, but I still want my ham radio related communications.

Besides which it's just more fun using radio to do things. I don't even use KJ4ERJ's excellent Windows Mobile APRS client because it's more interesting to see what coverage I get using radio, and radio gives me scope to tinker whereas with the computer/internet solution I'm just an appliance user.

LY2SS said...

I fully agree. And I am glad that you find the way to be a fraction, a tad independent from the Net. I wish we could buy cheaper handhelds with integrated TNCs available (even as an option). The current price is too high (comparing to current mainstream cell phones). You have a big APRS experience - in your opinion, maybe Chinese manufacturers could produce them? But would be sufficient demand for them? I'm afraid not...