Monday, March 27, 2017

Airband Scanners and the Need For Speed!

This is something I've touched on with a recent post when comparing the Uniden UBC125XLT with the Yupiteru VT225 and that is the speed with which a scanner will scan its memory channels (search speed is also important when looking for new frequencies too).

Many scanners available today offer scan speeds in the region of 20-40 channels a second which may sound quite reasonable. I think some of the AOR, Icom and Alinco radios scan at these sort of speeds and I believe the older Yupiteru scanners are in the region of 30 cps (channels per second) and many of the radio Shack/Realistic radios such as the PRO 2042 are in the region of 40 cps.

As I say that may sound reasonable, but when you have perhaps say 500 memory channels stored (quite reasonable even for airband especially if your interest is military and civil) it would take a scanner doing 20 cps 25 SECONDS to get round to checking each channel again! and when you consider that transmissions are often very short particularly on military airband you can begin to see that it would be possible to completely miss a transmission without ever being aware of it and then you're left scratching your head trying to lock on to that aircraft and the frequency it's using, so SPEED REALLY IS IMPORTANT in what determines a good radio scanner for locking on to those signals!

This is one area the Uniden radios in particular seem to excel, the 125XLT I have at the moment for instance has a published scan speed of 80 cps and I can honestly say, I've never picked up as many transmissions as I now do on this radio.If it's within reception range, I'll hear it.

My next intended purchase is a dedicated home based scanner and I'll probably be looking at the Uniden BCT15X as this has a stated search and scan speed of 100cps! I appreciate this scanner is not for the faint hearted as it has 'dynamic memory allocation' which I'm not going to explain here but it's quite a steep learning curve compared with most scanners today but I'm pretty familiar with the Uniden radios now having previously owned a 3500XLT with dynamic memory allocation so I think I know what I'll be doing with it so watch this space. Once I manage to get hold of one, I'll post my opinions and experience with it on here!

Sunday, February 19, 2017

Air Traffic Control and Bandboxing

Many of you are perhaps familiar with 'bandboxing' in air traffic control circles, for those that are not familiar with the term it basically means a controller is working more than one sector and/or frequency at a time.

Remember these? An early digital airband radio from Swinburne
For instance, the Daventry high sector for mainly northbound traffic over the east midlands uses 127.1 and the Daventry high sector for mainly southbound traffic over the west midlands uses 129.2. Now this morning (Sunday morning) traffic levels are lower and therefore one controller is working both sides of this sector and hence both aircraft and controller can be heard on both frequencies (transmissions re-transmitted on both frequencies). You may hear the controller on one frequency and the aircraft on another frequency.

This situation frequently occurs for me with Swanwick military central because I can always hear the controller on 252.875 UHF but if an aircraft is talking to him on his VHF frequency (128.7) I usually only hear the aircraft side of the conversation (probably different transmitter sites in use). 

Again, it can be down to a lot of factors such as your location and the location of any actual transmitter sites that 'repeat' the transmission from Swanwick etc.

But hopefully, that gives you an idea, I'm no radio 'tecchy' so would not even try to explain the more technical aspects of this!

Friday, January 13, 2017

USAF Reach flights

On a clear day I often see 'reach' flights crossing the UK, usually on a well used route either travelling east or west through southern Wales (sometimes further south using reporting point 'gitus' approx 15 miles north of Lands End) across to RAF Marham in Norfolk (and then on to 'navpi' in the north sea east of Great Yarmouth).

Aircraft using these callsigns typically include C130 Hercules, C5 Galaxy, C17 Globemaster and KC10 and KC135 Tanker aircraft and occasionally other types.

These flights usually cross 10-15 miles south of my location but are clearly visible from here in Leicester on a clear day. Occasionally their routing is slightly different such as 'reach 707' (C130J) early this morning that went straight across eastbound from central Wales (usually but not always heading to Ramstein) and passed almost overhead my location.

These flights are almost always working Swanwick military on 252.875 and usually a few miles east of here get transferred to Swanwick Military 'East' on either 259.6 UHF or 133.325 VHF.

Another common route for 'reach' flights is from the Northwest (Lake District or further North) across Yorkshire, Lincolnshire and then across the North Sea off the North Norfolk coast and from the Yorkshire area these usually work Swanwick civil control on 126.780 until passed to Maastricht when Eastbound.

I'd be interested in knowing the frequencies they usually work further North if anyone can help?

Monday, November 21, 2016

Uniden UBC125XLT and the battery save feature

I've mentioned before that the only slight annoyance with my Uniden UBC125XLT is the battery save feature which automatically kicks in after a couple of minutes when I am monitoring a single frequency and frequently means I miss the first second or so of a transmission which can be vital if the pilot is reading back a frequency change for example.

This feature is only apparent when connected to my small extension speaker as it generates a 'thump thump' noise as the circuitry is continually switching on and off!

The only 'workaround' I have found so far is to have one of the priority modes activated while monitoring a single frequency. My preferred option is the Priority DND option which checks any priority channels that are activated every 2 seconds as long as there is no transmission on the main frequency being monitored. With priority activated the battery save function does not 'kick in' at all.

Of course, you might say you don't want to be monitoring anything else, well if that's the case, if the frequency is in a memory channel, say for arguments sake, in bank 1 then make that channel the one and only priority channel allowed in that bank and only activate bank 1 for scanning, then put the scanner in hold mode on the frequency you want to monitor along with the priority mode and the scanner will be only listening to that channel and the battery save feature will not activate at any time!

The other option is the same as above ie. activate only the bank your channel is stored in during scan mode, hold on your desired channel, make that the priority channel and then activate 'Priority Plus' which will only scan priority channels in activated banks, so in this case, it will only monitor the one frequency in the one and only active memory bank.

Anyway it's not ideal, but it does work if you find the battery save feature an annoyance like me.

Friday, November 11, 2016

Yupiteru VT225 vs Uniden UBC125XLT

So, I've had an interesting few days with my Yupiteru VT225!
As soon as I got the VT225 'out of the box' I had forgotten how relatively small the LCD display is. I guess I've become very used to the nice big, bright display on my 125XLT!
After a relatively short period of time putting these radios side by side connected to my attic DIY dipole antenna (which incidentally, still performs better than any commercial product I've tried) what has become evident is that the VT225 was not pulling in any signals any better or stronger than my 125XLT! this was bit of a surprise, I really expected it to do better somehow.
With the radio connected to the attic antenna, it was pulling in all sorts of 'hash' and in fact, when trying to monitor Lakenheath approach which I regularly listen to on 309.200MHz, there was 3 signal bars of 'white noise' making it impractical to monitor. I also noticed on other frequencies where the background noise could easily be 'squelched out' I was getting the muffled breakthrough of strong local airways transmissions in places, something that I simply do not experience with the 125XLT. Don't get me wrong, the 125 is not perfect, there are a few odd frequencies that are susceptible to strong data transmission breakthrough in my location, but they are VERY FEW AND FAR BETWEEN. 
It's not all bad, I think the Yupiteru VT225 is a sensitive radio, but it is probably best used with a telescopic antenna attached directly to the radio itself and in the right position, is a very good receiver. Worth noting is that the audio quality on the VT225 is excellent and it has a very 'bass' quality sound to it. To get a similar quality of audio I have to attach a small usb charged speaker to the 125XLT. 
Interestingly, the scan rate quoted for the VT225 is 30 channels a second as opposed to 80 channels a second quoted for the 125XLT. When it comes to scanning airband and not wanting to miss the often, very short transmissions (particularly military) in my experience, SPEED IS EVERYTHING especially if you have several hundred frequencies stored in memory. 
All in all, I'm glad I took a trip down 'nostalgia lane' and it's made me appreciate what I have in the 125XLT - it is an excellent scanner for airband (and for the money) and the host of features and it's ability to reject unwanted signals have come along way since the Yupiteru scanner era of the 1990's. Do I sound like I'm on Unidens payroll? wish I was!
So what now for the Yupi? well it's already moved on to a new home! And my Uniden UBC125XLT is staying right here with me! 
What can I try next? fancy one of this little Icoms....

Monday, November 07, 2016

Yupiteru VT225 Civil and Military Airband Radio

I'm feeling a bit nostalgic and have decided to buy a Yupiteru VT225 airband receiver I found on Ebay at a reasonable price. I remember buying one of these brand new probably 20+ years ago now!

I remember being impressed with it's performance and ease of use so I thought it would be good to obtain one again and put it against my Uniden UBC125XLT just to see if it is a better performer. It will be a rather 'unscientific' test and I will simply see if the signal strength of ground stations I can currently receive is any better than the 125. In particular, I'll be interested in it's UHF performance which on any radio never seems quite as good as VHF primarily because the 'line of sight' physics become more critical as you increase frequency from VHF through to UHF.

If i decide to stick with it I will have to reduce my current frequency list down to those that I listen to most of all compared with those I have stored on my 125XLT as the VT225 has just 100 memory channels in 10 banks whereas the 125XLT has 500 memory channels in 10 banks. Also, I have come to love the 16 character 'alpha tagging' on the 125 so I can instantly see what I'm listening too! AND, for the first time in my many decades of listening, I'm able to easily program the 125XLT on my computer! 

I guess the performance of the VT225 will need to be measurably better for me to stick with it. The VT225 has been regarded as equal in performance to the venerable Signal R535 and are still quite sought after amongst 'us airbanders' so it will be interesting to see the results of my 'testing' once the radio arrives, watch this space for my findings....

Thursday, November 03, 2016

There be Dragons!

Just thought I'd mention an excellent blog for monitoring movements in and out of Fairford: As of today's date, there are two U2's on the ground that arrived yesterday (Wednesday 2nd November) and I also picked up 'Dragon 86' on its way into Fairford this morning on the London Military frequency of 133.900Mhz (Thursday 3rd November). Their callsigns always tend to be 'dragon' and quite frequently stop over at Fairford as they rotate their overseas deployments.

Incidentally, the author of the above blog also has a movements blog dedicated to Brize Norton activity here:

Sunday, September 11, 2016

Update on my Uniden UBC125XLT

I've had this scanner for quite a few months now and I have to say, I'm still very pleased with it.

There is not much I can find fault with at the moment but perhaps the only thing that niggles is the battery save feature (which can't be toggled on and off by the user) which works well, but does sometime mean that you miss the first second of a transmission which may not sound much but when an aircraft is passed a new frequency you can miss part of that frequency being read back by the pilot and so you can't be always be sure what frequency he has changed to. It's a little thing, I know, but that's it really.

I find 500 memories arranged in 10 banks of 50 more than enough and I now have my memory banks arranged as follows:

Bank 1 Swanwick & Scottish civil
Bank 2 Local airports (for me that's B'ham, East Mids & Coventry)
Bank 3 minor airfields inc. gliders, safetycom etc.
Bank 4 Swanwick military
Bank 5 Waddington & Coningsby
Bank 6 Mildenhall & Lakenheath
Bank 7 Brize Norton
Bank 8 Marham
Bank 9 RAF & USAF air to air refuelling
Bank 0 (probably tactical freqs when I get around to it)

The fact that I can upload all these frequencies along with the alpha tag names very quickly via the computer is a great bonus and something I've never done before. 

My latest DIY antenna in the loft is performing very well and I can hear ATC transmissions from both East Mids and Coventry loud and clear from my Leicester location and I can also hear aircraft reading back their clearance to land at Brize Norton some 62 miles away. Aircraft at altitude can be heard 150-200 miles away so I'm happy with my set up at this time. Obviously, the very best option would be an antenna mounted on the chimney but that's not an option for me right now.

It's just worth noting too, that when listening at home I have a small USB charged speaker plugged into my scanner which really does provide an audio quality on a par with a much bigger base station radio and can transform your listening pleasure.

I'd be interested to hear from any of you also using the 125XLT and what you think of it. Personally I find it a bit simpler to use than my 3500XLT for just airband listening.

Sunday, May 15, 2016

Airband Antenna

Until recently I've simply been using a telescopic antenna positioned in bay window of my bedroom where I receive the best reception.

I have now moved this into the loft and after experimenting on the best position (which is not always simply the highest I can get it) my reception has dramatically improved! I am still just using a telescopic antenna with a BNC connection to rg8 coax cable and what has always improved reception for me is having a similar length of wire hanging straight down 'trapped' in the earth side of the connector which is effectively creating a dipole type antenna.

My telescopic is extended to just under 23 inches (about 58cm) so it is tuned to 259Mhz which is precisely the middle of both the VHF and UHF airbands (118-400Mhz) and it is proving very effective.

For the first time in years, I paid the princely sum of £9.95 to try a Nagoya 771 dual amateur band antenna (2m/70cm bands) as I thought this might perform well as it is tuned for both amateur bands just above the civil and military airbands but in my very unscientific testing alongside the telescopic it was definitely poorer reception so I'm sticking with my makeshift antenna for now, oh well, for only £9.95 it was worth a try.

What I have learned over the years, is that depending on your location and what specific ATC units/airfields you want to hear the most, antenna height is not always as important as the location of your antenna, happy listening!

Friday, March 11, 2016

Airband Reception and Fog!

I woke up this morning to find that it is quite foggy outside. It's worth noting that reception on VHF and UHF frequencies which includes the airband frequency range, is often much better when there are fog conditions.

I don't want to start getting into technicalities here, but when there's high pressure and fog, it can have an effect on radio wave propagation in the troposhere (the lower level of our atmoshere) which affects airband reception. 

This morning is no exception, as I am receiving East Midlands ATC (about 15 miles from me) much louder and clearer than usual and there's a distinct improvement in reception of aircraft and maintenance vehicles on the ground at East Midlands Airport.

So, it's always worth scanning around in fog conditions to see what signals you can 'pull in'. I remember on one occasion, I was clearly receiving Gatwick approach ATC on 126.825Mhz from my location near Leicester! but that was exceptional and doesn't represent the norm.