Thursday, 4 May 2017

WSPR from Mallorca

A few weeks ago I was in holiday in Mallorca (El Arenal) and took my WSPRLite with me. I'd been thinking about using a balloon to hold up a half wave for the 20m band but didn't see any balloons when I got there so had to rethink.
In the end I used the Snowdonia Radio Company UnUn feeding into the ventilation duct up the side of the hotel, with no idea what the SWR might have been. Some RF did manage to escape though, 106 stations reported me on 14MHz WSPR that week, the furthest being OY1R in the Faroe Islands at over 2500Km away.


We were on the 4th floor, so the feedpoint of the 'antenna' was about halfway up.
I also took my Baofeng handheld to see what other radio activity there was on VHF/UHF. Heard some amateur repeaters in the 70cm band (repeaters over there transmit in the 438-439 MHz range) but they were all digital. For people visiting the island it's a good thing to have digital repeaters that can be linked up.
Repeaters on 438.250 (DMR), 439.200 (D-Star), 438.450 (D-Star). Page with all Spanish 70cm repeaters.
No analogue repeaters or simplex heard at all on the amateur bands, and a lot of activity on other frequencies was DMR.
The FM broadcast band in Mallorca is very busy, with the main broadcast site at Bunyola having 25 different transmitters, and another at Palma with 18. Many transmitters at Bunyola are only 300KHz apart, with a couple at 200KHz spacing!
 The masts at Bunyola, about 25km away to the north.

A few people on HF nearby

Lots of Ubiquiti 5GHz Wi-Fi links

Monday, 27 March 2017

Good VHF/UHF Conditions









On Saturday, conditions on VHF and UHF were really good. Hearing a lot of activity from Ireland, and even signals from as near as Blackpool were a lot better than normal.

The video is just my radio scanning round 2m and 70cm, showing what kind of signals I was getting from some DMR repeaters, the best propagation was to GB7UL on 439.525 at Carrickfergus.

On 145MHz, GB3MP on 145.750 was a bit stronger than normal, you can hear some interference on all the VHF signals, like a clicking noise. This happens at certain times of day, and is on top of the already high noise level - if I turned the squelch down on the FT-7900, it would be showing S3 of noise right across the 144MHz amateur band.

I could hear a repeater on 439.100 which had an Echolink conversation on it, that isn't a repeater frequency used anywhere in the UK for analogue or digital, and the only mention I could find online was a repeater in Germany. I couldn't find any CTCSS tone when scanning for one either.

Friday, 17 March 2017

How Cheap?

Think £20 for a dual band handheld is a bit too much? Well how about £9.36 for two?
http://www.ebay.co.uk/itm/2PCS-2014-UV-5RA-UV-5R-Dual-Band-136-174400-480-MHz-FM-Ham-Two-way-Radio-/332156764896?_trksid=p2141725.m3641.l6368
If you look through enough search results on Ebay for Baofeng radios (either the UV5 or the BF888 single band 16-channel) you find the odd one on sale for ludicrously low prices.

Here are UHF handhelds for under £2 each
http://www.ebay.co.uk/itm/Baofeng-4PCS-Walkie-Talkie-UHF-400-470MHZ-2-Way-Radio-16CH-5W-BF-888S-Long-Range/132121923681?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D38c967ad568545deab73661a4b153f52%26pid%3D100338%26rk%3D2%26rkt%3D18%26mehot%3Dpp%26sd%3D332156764896
At this sort of price, even if the battery or the radio was faulty when delivered, the other half would still be worth the money as a spare.

Friday, 3 March 2017

Audio Transformers

I ordered a Ground Loop Isolator from Ebay a few weeks ago for about £2 - a box with 2 audio transformers in it, usually for installing in a car between the line out of a car stereo and an amplifier. I got it for connecting between a radio and PC, in case there were problems with ground loops and other interference.


And here are the transformers inside
I have my Yaesu FT-7900 connected to a Edirol UA-25 USB audio interface using a 6 pin mini DIN to phono cable. One phono plug for discriminator audio (9k6 packet out) and another for normal (voice) audio. The first test I did was to try decoding some DMR using DSD+ software. This normally works OK using the 9k6 packet output.
DSD+ was trying to decode the DMR but there were so many errors it could not even get the correct colour code on a strong signal. Definitely the transformers causing the problem.
I checked their frequency response by looping the UA-25's output back to the input and playing some test tones through it, then comparing with a straight through cable.
The table below shows the insertion loss at each frequency compared to a straight through cable.
The -3dB point is somewhere between 50 and 100Hz, this would be OK for voice and data which used frequency shift keying only within the normal audio bandwidth of a radio, but for DMR (and probably other data modes using the same modulation), this is no good. It cuts off a bit high for music too, at least with a good amp and speakers.

Wearable

Last June I started trying to be a bit more fit and healthy so as well as joining a gym, I bought a fitness tracker "smart watch" device, a Garmin Vivofit 2
It's purely a fitness tracker, it won't show messages or do any syncing with a phone other than to (slowly) transfer my activity data.
But, unlike a lot of other wearables, it uses a non-rechargable lithium cell (CR1632 - not a very common size, couldn't find any in Poundland so ordered some spares online) which can last up to 12 months. I've not had to change mine in the 9 months I've had it. It's waterproof and I've never needed to take it off.
As well as steps, it can measure heart rate (with a chest strap which I've never tried) and sleep (by tracking movement, not by brain waves or anything as clever). I usually keep an eye on steps and distance throughout the day, walking a bit more in my lunch break since I've got it.
At the gym it's sort of useful, some of my gym activity adds to the step and distance count but it's no use on the bike and might not be that accurate on treadmill and cross trainer as the movement isn't natural walking or running. The daily step target varies depending on how well I've done over the last few days, it's usually over 10000 unless I've spent a few days off work doing nothing.
Here are a few screenshots from the Android app, Garmin Connect. I find that to sync the device, I need to start the app, kill it in the task manager and then start it again before pressing the sync button. The app also needs internet access to work at all, it won't even sync offline as all the data is stored on Garmin's servers.


 My best 28 days was around 400000 steps, in the summer.
My phone also has an activity tracker, Samsung S Health, which is always running but I don't take much notice of it as I don't always have my phone with me when exercising. It usually says I've done enough steps each day anyway but I think the target is set to something really low like 6000.

Monday, 27 February 2017

LoRa

200km from a low power 868MHz device?

https://www.youtube.com/watch?v=adhWIo-7gr4

See this video for very long range experiment using LoRa modules. LoRa is a spread spectrum (125KHz bandwidth) data mode which can be received at very low signal levels, and its main use will be for the Internet Of Things - smart meters and other stuff which only needs to transfer a small amount of data. This is all done in licence free bands that are normally used for low power data such as remote controls.

https://www.thethingsnetwork.org/

There is also The Things Network, connecting LoRa gateways around the world which anyone can access (it's a bit like the amateur radio APRS gateway system but for LoRa devices). There are already a few set up in the Liverpool, Manchester and Lancaster area.

The YouTube channel above has instructions on how to build both a node and a gateway for LoRa. 
You can get LoRa modules for the 433(in the amateur band but low power devices are used here), 868(main band in Europe) and 915MHz (USA) bands.

It's interesting to see that there's so much experimenting with radio going on outside of the usual amateur radio bands and organisations. To me, anything that could possibly get more than a few hundred metres is worth trying (further than your average indoor Wi-Fi access point).

Monday, 6 February 2017

WSPRlite

My WSPRlite arrived on Friday, from SOTABeams. A 200mW WSPR transmitter, needing no PC or any cables except power (micro USB) and antenna (SMA).



And while I'm taking photos in the kitchen, here's Friday's tea


One button, one LED. Press the button once at 2 seconds past an even minute to begin the first transmission. I use the Clock Sync app on my phone to get an accurate time via the internet.

I've no permanent HF antennas at home so I tried it in the car, with a Watson Multi Ranger antenna. The mag mount is a bit small for the HF bands but I found it worked OK on 14MHz, with 20 reports in the first hour of use. I powered it from a TP-Link power bank, and at 180mA on transmit and under 50mA waiting, it will last for days on that. My USB power monitor won't measure below 50mA so read zero except when transmitting.
At that low power, most SWR meters won't let you calibrate to full scale, but as long as they have a separate reverse power reading, you can see when the SWR is OK (3:1 would be 25% reflected power, 2:1 9% etc.).
 No connection at all to the car electrics

 The next time I tried it in the car on 14MHz, I got 2 reports from the USA.
Compared to the usual 5 watts I'd been using for years on WSPR when I had a proper HF radio, 200mW (14dB down) needs a bit more effort - 5 watts will work into just about anything with WSPR, especially with an auto tuner. At 200mW an auto tuner might not even start to tune on transmit. I think the mobile whip is just as efficient as a random length of wire.

On Saturday I made my first SOTA chaser contact on DMR (or any digital voice mode). I've made QSOs from summits on both D-Star and DMR before though. When I was scanning round, I heard some activity on 438.6125, so quickly changed over to the DMR radio and spoke to 2W0SEY/P on Moel Famau (G/NW-044).

For tea on Saturday we went out to One Restaurant in Barrow. The last time I'd been there was 3 years ago for my birthday and tried The Challenge of eating a massive burger, hotdog and fries in 45 minutes (and failed). This time I settled for the normal menu
 "Alligator Cooler"
 Piri Piri Burger
Chips, Cheese and Gravy
"The Black Hole"