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"


Wednesday, 1 February 2017

RF Explorer

Some channel power measurements (all in a 5MHz bandwidth) on my RF Explorer on the tri-band colinear.
I've had the RF Explorer for over 5 years but only just tried the PC software for it.

930 - 935MHz: O2 (3G) base stations


 390 - 395MHz: Airwave TETRA base stations

955 - 960 MHz: O2 (2G) base stations



452.5 - 457.5 MHz: Various business radio users, mostly continuous trunking data and DMR



 950 - 955 MHz: Vodafone (2G) base stations - a lot lower than O2's sites here

I've ordered a WSPRlite to get myself back on HF, if only at very low power.

Monday, 30 January 2017

Tardily Cohorts

Post title randomly generated

145.500 activity from this weekend recorded at home -
Saturday 28th January
CQ call early on but couldn't get callsign properly - possibly M0CQE?
GW7HEM/P - Foel Fenlli SOTA GW/NW-051
GW4TJC/P on Foel Fennli and later on Moel Famau GW/NW-044
2E0LBI/P on Birkrigg Common
GM3VMB

Sunday 29th January
2E0KUK/P Great Whernside SOTA G/NP-008
M5CMO/P
G4RQJ/P Gummer's How SOTA G/LD-050
G6ZET/M

Monday, 23 January 2017

Billinge Hill 2017

Last Wednesday (18th January) I was in the Liverpool area and did an unexpected activation of Billinge Hill (SOTA G/SP-017).
All I had to use were two handhelds, both with their own antennas. As one of them had DMR, I tried putting some calls out on 438.6125 and posting a spot on the Sotawatch web page. This was a weekday afternoon so not the best time for any activity and got a total of 0 DMR contacts.

 On 145MHz I was using my new Baofeng GT-3. I already knew that this was pretty rubbish on VHF for handling strong signals (at home on my outdoor antenna it was completely overloaded, even though there were no very local VHF transmitters - maybe from FM broadcast or DAB signals then). Billinge Hill is one of the worst places to take any radio that can't handle strong VHF signals, but I did manage to make 2 contacts with stations who would have been S9.



 I almost made a contact with M6BWA/P on Titterstone Clee Hill (SOTA G/WB-004) but I think at both ends we had problems with nearby transmitters and couldn't get more than a few seconds of unbroken reception. Fortunately M0JLA/P was also at the summit there and I spoke to him on 70cm using the other radio. It was like one of those times when it's a big relief that there's a 5th contact from a SOTA summit, because the 4th was a bit suspect - did you really get all their details? was someone using 2 of their own callsigns?


On 70cm I got a few more contacts and there was a lot less interference, but it wasn't 100% noise free - the strongest UHF signal up there would be Airwave, with no UHF business users there any more. I wonder how that would have affected DMR - it's easier to tell on FM if there is interference because you can hear it, with digital voice there would be drop outs or just silence.


I parked at around SD524021 on the road north of the summit which is just below the activation area (unlike every other time I've been up there) and walked past the buildings before crossing the fields. As it was an unexpected activation, the white trainers I had on weren't the most suitable footwear for crossing the muddy fields.




Weekend Calls

Saturday 21st January
Didn't do the usual 145.500 recording, instead I left the FT-7900 scanning 4 digital voice channels
144.5875
144.6125
438.5875
438.6125
(.5875 is the most popular DMR frequency near me)
with the squelch turned down and decoding the 9k6 packet output with DSD+. This checked each channel for about 5 seconds before moving on.
Total activity during the daytime was one station - 2E0LBI

Sunday 22nd January
Recorded 145.500 as normal.
CQ calls heard from
G6PJZ/P CQ SOTA. No summit given but was spotted from G/NP-022 Calf Top so probably there.
M0HQO/P CQ SOTA. I wish people would say the summit name on the calling frequency and save me having to look it up! Spotted on G/NP-008 Great Whernside.
G4RQJ/P CQ SOTA from G/LD-052 Hutton Roof Crags.
G7PAJ/M calling from Kirkstone Pass. Didn't seem to have any replies.
Someone else mobile might have called CQ in the afternoon but their audio was very low, someone did reply to them though.

Also been using the Last Heard feature of the Retevis/Tytera modified firmware and leaving the DMR radio scanning simplex channels.

Sunday, 15 January 2017

#6 Poundland Power Bank

Not a lot of activity to report on 145.500 so far this week, recorded all Thursday 12th and not a single CQ call from 6am - 10pm.
Saturday 14th wasn't much better, between 9am and about 3:30pm there was one single station - G6ZET in the Lancaster area.
Sunday 15th was slightly better, with G8INU and 2E0DVV calling. But this weekend not a single portable station, must have been the weather.

Not long ago I was in the local Poundland and spotted some rechargeable USB power banks.
Sold as 1200mAh (4.44Wh). When I tested this from full, charging a tablet, it ran for about 70mAh at 5v output then gave up. Tried on a lower current load, with some LEDs and it ran for a total of 170mAh (850mWh). Even with any conversion losses, there was no way the cell inside was 1200mAh (a proper cell of that size would be rated around 2200mAh). 
I'd avoid any power bank of that design, or anything battery based from a pound shop.

Wednesday, 11 January 2017

YouTube Channels

A couple of good YouTube channels I subscribe to, with all kinds of amateur radio/drone/e-bike type stuff

Andy Kirby

Distant Signal

Monday, 9 January 2017

Activity 8th Jan

CQ calls heard on 145.500, at home, Sunday 8/1/17 (the whole day apart from when I was using the radio):
GM3VMB - Annan
The area round Gretna and Annan is a good VHF path for me, over just the highest points of the Lake District fells.
M6VMS/P on SOTA G/LD-018 Stony Cove Pike
2E0DVV - Ulverston
G8INU - Blackpool area
G8BEK - Burnley
I also do quite well towards Burnley, Walney Island being as far back as possible from the Forest Of Bowland probably helps.

Saturday, 7 January 2017

Today's S20 activity

People calling CQ on 145.500 today, on my recording made at home between about 9:30am and 4pm:
  • M0BKQ/P on Whernside (SOTA G/NP-004)
  • M0KCB/P - no summit references given but the first call was for both SOTA and WOTA so looking at the WOTA website, shows an activation of Gummers How (LDO-067) in the morning. A later call was "CQ WOTA" only, so probably Staveley Fell, (LDO-084).
  • G8INU (Blackpool area)
  • Some stations calling others
 Other stations heard
  • 2E0MVH calling through GB3MP 145.750 - spoke to Sean on the repeater (it's a while since I've been on MP!)

I spoke to M0BKQ/P while I was out in the car this morning, first SOTA chaser QSO and first voice QSO of 2017.

If you do put a call out on 145.500 at the weekend, even if you don't get any replies, there's a good chance I'll have heard you if you're within VHF range. Weekdays I usually run the APRS gateway instead. I'm going to try and post as many reception reports as I can from the calling channel, if I'm recording or not able to get back to someone.

Friday, 6 January 2017

#2 Homeplugs

Bought a set of TP-Link TL-PA4010 Homeplug power line network adaptors a few weeks ago. I'm not usually a fan of these things as they use radio frequencies that get radiated by the mains wiring but at the moment I've nothing for the HF bands so it doesn't matter. They were also under £20 for a pack of 2.
They are supposed to be 500 Megabit but as they only have 100 Meg ethernet to connect to anything, that's a meaningless figure, even if they could manage that in ideal conditions. Anyway I set them up by doing the usual button push and they worked as well as the Wi-Fi from router to the bridge I use to connect my main PC wirelessly, with our FTTC broadband.
If they aren't 500 Mbit/s, then how fast are they in real life? I did a test with them, compared with Wi-Fi over the same distance.
For the test, I moved my D-Link DNS-320 downstairs to the living room. It's usually plugged into a gigabit switch next to my main PC. The 'fibre' modem and Wi-Fi router (Plusnet branded Technicolor TG582N) are under the TV in the living room. This is a 2.4GHz only device, with no external antennas and 4 100 Meg ethernet ports. 



Wi-Fi test
 I plugged the DNS-320 into an unused port on the router. I set my Wi-Fi bridge up again that I had been using before I got the Powerline kit, and the main PC was connected through a gigabit switch to this. Usually I power the bridge through the DNS-320's front USB port but the iPhone charger is powering it now.
I copied a 3GB file from the NAS (mapped as a drive letter in Windows 10) to the local disk. Here is a graph of the transfer

Even though the Wi-Fi kit was capable of 'N' speeds, the connection was only being made at 54Mb/s. The maximum speed just hit 40Mb/s, which is about 4.5MB/s of file transfer. This is barely good enough to make full use of my internet connection (paying for 38Mb/s but the line can do at least 65Mbps). 

Powerline Test
For this, I plugged the DNS-320 straight into the Powerline adaptor downstairs (it has a static IP address) and the upstairs Powerline into the gigabit switch.


Both devices were on the same ring circuit (House Sockets) - there is a second ring circuit for Kitchen Sockets, which might affect the speed as there is extra cable and circuit breakers to go through but these are the most typical places you would plug in powerline adaptors.

Powerline beat W-Fi by 75% over the same distance, copying the same 3GB file. 
It was also a more stable connection, giving over 7.5MB/s of file transfer. 

The interference given out by these on HF affects mostly those frequencies outside of the amateur bands, as amateur radio frequencies are notched out, with about 50KHz guard band at the edges. On other frequencies though, there is a lot of noise from them, which even on a portable radio can be heard out in the street. When they are idle, the noise is a bit like car ignition noise (very short pulses which may be caught by the radio's noise blanker), but as soon as any data is transferred, the noise becomes continuous. Below 27.95MHz there isn't any limiting of interference to the CB channels.

What would you need them for?
For most people using Wi-Fi devices around the house on the internet, not very much. I don't like Wi-Fi on desktop PCs, as any antenna is going to be round the back, between a metal case and a wall, surrounded by a load of cables (or it's going to be inside a metal case). It's also another thing to install and take up a USB port if it's a USB adaptor. If you have some kind of file server on the network, it's good to have it wired to at least one PC/Mac to get stuff onto there quickly. That's when you would have a permanent link back to wherever the internet and Wi-Fi was coming from - ideally wired but powerline or Wi-Fi bridge if that's not possible. 
But if you live anywhere near me then absolutely DO NOT buy them (or get Sky Q)!

The network in the home is actually the bottleneck now in most areas - it can be faster to download even a big file from the internet than to transfer it over Wi-Fi between two devices in the same house (everything has to be transmitted up to the access point then back down).