Raspberry Pi Dvap Hot spot Controller

So, as promised, here are the details on my PidVap.  Thanks to John, N3SBP, for turning me onto this information.

What you need is a Raspberry Pi Model B, a 16GB SD card, and a DVAP, either VHF or UHF, whichever you prefer.  Then I just simply followed the instructions found here:
http://ncmd-dstar.org/downloads/raspi/NCMD_RaspiberryPi.pdf  

That PDF gives you this Download link: http://ncmd-dstar.org/downloads/raspi/NCMD_Raspberry_DVAP_Node_V3.zip

Which is an image file for your OS that lives on the SD card of your Raspberry Pi, this image includes already the software for ircDDB and another piece of software called DVAP Node.  After that all you have to do is follow the instructions to set up the controller with your callsign, etc.

One thing that was a gotcha for me was that I did not realize that I needed to put my radio into Duplex mode.  For whatever reason, I think the radio doesn't send out the proper commands for a repeater operation if it isn't in DUP. So you set the offset to 0.00Mhz + or - and it sends out repeater commands when you key up.  Without doing that you can not link to any reflectors or repeaters.

If you can not get into the router that you are connected to in order to get your IP address that allows you to connect to the Pi remotely, so that you do not need a monitor and keyboard, etc. connected to it, there are these two options as well.  I haven't yet tried either option, so if you do let me know how they work, and if there are any hang-ups, etc.

·       Send IP Address from DVAP/Pi via Text Message to cell phone - installation and configuration guide:
http://ncmd-dstar.org/downloads/raspi/Send_IP_Instructions.pdf

·       Speak IP Address from DVAP/Pi via 3.5mm Audio Port – installation and configuration guide:
http://ncmd-dstar.org/downloads/raspi/Speak_IP_Instructions.pdf

There you go, I hope you enjoy that.  It was super easy for me, and I find the tool very useful, now I can just leave my Dvap constantly running, no need for a PC running an application all of the time, just a little Pi hiding somewhere behind your router controlling the whole thing.  So far it has performed flawlessly for me.

Cheers!

73

AJ4TW

Moving . . . Again!

Well, life has taken another turn, and my wife and I are headed back to NC.  This means that I've already packed up my HF station for moving, and I'm not sure when I'll be able to set up HF again.  So for now, I'll  be on Dstar and FM V/U for a while.

I believe this will lead to good things for my wife and I and I can't wait to start over at a new location.  I'm hoping this QTH will be one we remain at for many years.  We have moved so many times over the last few years that it's hard to keep up with.

I will still post a few things, I'd like to publish a post regarding my Raspberry Pi Dvap set-up so that others can do the same. It works wonderfully.  Look for some specific information on that coming soon.

Cheers! and 73
AJ4TW

Limited Time

Every ham dreams of having more time on the radio, well, at least I know I do.  More time on the radio, more time to play with antennas, more time to build a kit, and even more time to set up your software.  Unfortunately real life gets in the way, even when we think we could make do with what we've got, we still have to eat.  Today was no exception, very limited time.  I sneaked into the shack and knocked out a few QSO's this evening after hours at work, we were working a little late tonight, but I could not resist when I heard CT9/DJ8OG  on the island of Madeira soon after that I heard a station on Galapagos, HC8/G8OFQ  Tis the season I suppose for Hamcations, boy am I jealous.  Anyhow, I was thrilled to work them both on the first call each.   So much fun.  Thanks to Chris, K4HC for sharing this little gem with me:

A Good Blast on the Radio to Start off the morning

Just as Rick at the VK2GGC station said to me the other morning, "There's nothing like a good blast on the radio to start your day off."

I was able to work Japan this morning on 20m, JH3NGD Kazu, it was a great contact, very enjoyable to be able to communicate around the world directly with your own equipment.

Love a good blast on the radio.

30Mhz to 6Ghz HackRF

Well, I became a backer, I have a long wait at least 5 months until my HackRF peripheral shows up.  I'm a little nervous, but, I'm excited to play around with it and explore some of those microwave bands.  I will be sure to take lots of pictures and screen shots when it arrives.  Long Live SDR! 

Contesting Observation

You know, I notice this all the time, three or more stations piled on top of each other when there is plenty of room to spread out.  Why does this happen?  Don't have enough time to spread out far enough so that you can at least hear who's returning your call?  Wouldn't your rate increase if you had a clear section of bandwidth?  In the picture below you can see two instances of it on 20m.  Maybe they can't hear each other, that's always a possibility I guess.

Wasn't the DEXP

When I actually sat down in front of the F5K I could clearly see that it could not have been the DEXP that was clipping my audio, it was off.  Durp

So, I played a little more with the VOX, I turned the delay up from 250ms to 500ms, which I think is actually a little long, it should be maybe around 350, I'll try that, it's just hanging in there a bit too long, but doesn't cause any real problems.

I also lowered the VOX setting as well I had it about 140 and I've moved it down to about 100.  I want to be able to adjust the boom on my headset without having the noise of it key up the radio.

So, I think it's mostly fixed, just needs a little fine tuning.  I think my audio is a touch on the hot side right now, not terrible just a touch too hot.

Very good morning however, I came into work this AM and caught up with two Australian stations on the 20 meter band.  VK5CE/P and VK2GGC.  I recorded the QSO with VK2GGC Rick was the operator, nice little conversation.   I looked them up on QRZ afterward and I found that VK2GGC is the call sign of the Girl Guides Callemondah. They have a nice couple of YouTube videos up as well. I like this one a bunch:

Girl Guides Callemondah VK2GGC contest Video

Downward Compander

I think I have it set too high.  Listening to some of the recordings I noticed there was some clipping of my audio, no one has mentioned it, but maybe if I got into a little rag chew they would?  I thought it was probably that my VOX sensitivity was set too high, so today I lowered my VOX setting.  But, that did not help.  I had a little revelation, I think it might be the downward compander, I'll try turning it down tomorrow or the next day and see if that helps.

I've been having a little fun with recording QSO audio lately.  My brothers pointed me to soundcloud so I uploaded a few there today and added some soundcloud widgets to my blog.  I have to admit it's just a little creepy that my google log in get's me into all this stuff, does google own everything?

17m has been great lately, very open and lots of fun for such a narrow chunk of bandwidth.  I caught 9K2YM this evening on 17 just after he announced he was going QRT (ceasing transmission), I usually let them go, but I'd been calling and calling, so I thought, what the heck, I'll give it one more last shot.  And he came back to me, pretty cool.  He gave me a 5x9 IDK if that was a habbitual "five nine" or if it was a real report, I gave him a 5x7 because that's what he was, and then he really went off air.  

I love how each band we have has it's own unique personality, you get to know it, start learning it's little quirks, what it likes and doesn't like.   So much fun, I'd never really spent much time on 17 before, but I sure am liking it lately.

 Click here for the RFI Video

Here is a little clip of the noise at 15.250Mhz picking it up with the HT and the Radio.  I am fairly certain it is coming from outside the building, or at least from one of the units on the roof.  Maybe nothing I can do about it in this commercial environment.  I'd love to power down the entire building but that's just not going to happen.  We share the building with Loudoun Co. Fire/Rescue maintenance garage, and as I said before we have a SCIF that kinda makes shutting things down a little complicated.

I worked Guyana for the first time yesterday, it was a difficult contact for me because he was not only wedged between two european stations(IDK why he was there, maybe he didn't hear them but he only had about 1.3Khz space between them.) but he was also centered up right on one of these noise spurs that I have.  But we were able to talk, Thanks to the filtering capabilities of the F5K I was able to pull him out from around all the QRM/QRN.  :-) 

Broadcast Band Filter

I got this filter in today and installed it.  It made a huge difference, I will post some measurements later on.

Front End Overload.

I have found the source of my high noise floor.  There is a 50,000 watt am broadcast station only two and a half miles from me.  50KW!!  As you see below it is FULL scale into my Receiver, and I can see it on every band almost now, any time I am in AM mode for sure I can hear it.  This is a new occurrence because since my last post I put up a 43' vertical for HF.  My solution is going to be a broadcast Band filter, as suggested to me by some fellow hams, hopefully that will knock out all of this interference that I am seeing from WCRW.   Here you can see 1190 AM -1.7dBm into my front end. 

Here on 10m you can still see the interference from that station.

and 12

and 15

and 17

you can also see that I have a very high noise floor in all of these bands, I am hoping very much that this filter will knock all of that noise out and let me operate HF in the clear!

Special events and Contesting help you learn your station.

I spent a modest amount of time operating this week as K2B the www.13colonies.info call sign for the state of Virginia.  There were four of us operating from VA.  I spent about 9 hours operating and made 775 contacts.  I had about four of those hours where I was making about 70 contacts an hour or more.  And about 5 hours that were much slower paced.  The conditions were rough this week for me.  There was a ton of QSB(fading of signals on the band) and my noise floor at times was higher than the signals of over half of the stations I was working.

I learned something very quickly, I was being heard a lot better than I was able to receive.  I operated my Flex 5000A at it's full output, 100W, into a 17' tall vertical antenna on the roof of my office at work.  The roof is metal underneath a layer of rubber and gravel, it's called a ballasted roof structure, the gravel holds the rubber down on top of the insulation which is on top of the corrugated steel roof.  I have braided grounding straps running from the antenna grounding systems and the Flat roof antenna mounting structures.  So the idea is that the metal in the roof will act as a counterpoise to the antenna system, or a ground plane if you like.

I had been observing a high noise floor on 20m for a few weeks.  With that in mind I bought a piece of 3/4"x6' copper tubing, and some 12"x1" braided grounding straps.  On July 4th, as you see below, I used those supplies to construct a station grounding system.  It's basically an RF/DC ground.  I pounded the tubing flat with a dead blow hammer, then drilled six holes in that spaced out near where the grounds are for the various pieces of equipment on the shack desk have their ground terminals.  I ran the braid from the equipment, F5K, Two Power supplies, an Icom 746, and an MFJ 946 antenna tuner, as well as my little IC-2720 V/U rig.  This helped a bunch with the noise floor, lowering it about 5-10dB.  So at this point I got an S5 or so noise floor.

But my receive was still not as good as my transmit, in fact, my transmit efficiency got even better, which sort of compounded the problem.  The problem was that guys were hearing me S9 and S9+ and I was hearing them in the noise.  I think there are a few problems going on.  Capture area, I think maybe this antenna is just too small to capture a lot of signal, even though it is about 1/4 wave antenna, it's just not a lot of capture area, a half wave dipole would be twice as much.  Another problem I think is the vertical polarization.  I am in an industrial area, and a lot of the noise I get is vertically polarized, just wait until the behemoth across the street goes on line(more on that another time).  Also, I think that I still have a bit of a grounding problem.

It is important to be able to receive when you are running a contest or special event.  Just being heard is not enough.  With 100w more people could hear me than I could hear, imagine if I had 1500watts and a receive problem!  That is where the classic Alligator sation comes from, all mouth no ears.  If you can't hear them you can't work them, it's a problem, and a problem that makes you look like an appliance operator instead of a real radio station operator that understands his equipment.

So what to do about it?  Well, that's for another day, I am still thinking about that.  The obvious(to me) answer would to be to get one of my beloved balance line fed doublets up in the air.  But my QTH presents some challenges with that.  Flat roof with no existing structure to get a horizontal wire antenna up.  Oh, and a limited budget, and limited lattitude.( I don't think my boss will go for a SteppIR on a roof mounted tower)

Any ideas?  feel free to comment and help me brainstorm.

73
AJ4TW

Improving the station ground.

Working as K2B for 13 Colonies special event.  Lots and lots of noise on the bands and hard to copy stations.  So I thought the time is right to finally utilize the supplies I had gathered.  Hopefully this will help with some of the noise.