Control and Programming Software for the ubc125xlt

One of the things ive found playing with my new toy, is that controlling it is not exactly the most intuitive process! It does take a bit of getting to grips with, and the manual, although not Chinglish, is far from straightforward or well laid out.

Direct entry of a frequency, and its storing in memory, is not as simple as my venerable MVT-7100, but then, the Yupiteru doesnt do alpha-tagging to allow naming of stored channels. So the entry of more than a couple of frequencies is rather tedious and tiresome.

Luckily, a chap by the name of Nick Bailey has created a Visual Basic program to program and control the scanner from a PC.

Scan125 is the programs name, and it can be obtained from http://www.nick-bailey.co.uk/scan125/ 

Its takes a little time to find your way around, but its certainly much easier than direct entry! Especially as the entire scan banks can be edited on the PC, handy when first setting up with a lot of channels to enter!

Two things with it though, first, you must follow the instructions to set up the driver for the scanner properly. Its simple but different! Second, a splash screen will annoy you every 10mins if you dont register the software. Registration is easy but he does do it by a rather odd method involving a lot of clicking of mouse buttons.

For many people, especially those who are new to the use of scanning receivers, the big problem they have is finding something to listen to! Here, I would always suggest to start with the VHF Airband, as there are always signals there. Beyond that, many people give up quickly due to not finding anything to listen to, as the patience required seems to be beyond many. To this end, I would advise at first start up to chuck the PMR446 and UK 'Simple' Business radio frequencies in. These are very widely used due to the low licensing costs (free for PMR446 and £75 every half-decade for Simple).

Those coming to the hobby with a view to listening to the emergency services or mobile phones (as per the good old days!) - FORGET IT!!!


On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

New Toys

As my main interest in general utility listening is more geared towards intercept and identification rather than content, I decided I would finally treat myself to a bit of new kit. I looked at the cost of DMR and dPMR capable scanners, but they are still very much out of my range, and besides, SDR is in many ways a more fitting system for such modes.

So I dropped on a Uniden Bearcat UB125XLT handheld scanner, 2nd hand for a good price. The attraction of this device is Uniden's 'Close Call' feature - a strong signal intercept mode.

The above of course is a stock photo (the giveaway is the model number which has clearly been over-typed! I suspect the original photo was of the US market 125AT version!).

One very useful modification that can be made to scanners is to provide a high impedance raw audio tap from the discriminator. This is very easy to do on the 125 as the headphone output connector is stereo but the unit of course mono - giving an available connection. It just requires the removal of the L- and R- balance resistor, and the addition of a 10k resistor and wire between the discriminator and the audio socket. Rather conveniently, all the important signal paths in this receiver have nice big test points!

 All the photos above show the receiver in various states of dismantlement. The photo of interest is the one bottom right, this is the RF board. The big chip to the left of the IF filter (the big cream block on the lower right) is the IF subsystem IC, to the left of this is a large test pad for the discriminator output, marked DISC. At the top of the board between the BNC socket and the volume pot, can be seen the 3.5mm stereo jack socket. Just below that the balance resistor.

Later today I will perform the discriminator mod. But only once my workshop has warmed up!

On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Software Defined Radio and Pager Decoding

Ive been playing again recently with my cheap R820T RTL dongles. These, when used with suitable custom drivers and SDR software, are interesting devices allowing for the reception of all manner of signals.

In this case, ive been using mine with the SDRsharp software package to control them (referred to as SDR#), and playing with attempts to receive and decode digital audio and trunked network signals. Ive not had much luck that way yet, but what I have had success with are pager signals.

Some of you reading this (I suspect most of my readers!) will be old enough to remember the period in the mid 1980s to the early 90s when mobile phones were the size of a housebrick, public payphones either vandalised or used as conveniences, and the alternative to a landline the very short lived Rabbit DECT system!

During this telecommunications chaos, those who wished to look like Yuppies but without the budget for a phone, carried a pager. My mate Ian had one - I dont actually recall it ever beeping! ;-) Most people think these legacy devices are obsolete with the coming of GSM phones, but no, they still exist, now used mostly for alerting on-call staff, sending telemetry messages, and are also now a valuable part of the emergency services response systems.

These devices live on the VHF bands around 138MHz and 153MHz. Two protocols are still in general use - POCSAG (Post Office Code Standards Advisory Group) and FLEX, at several baud rates from 512 and 1200 (POCSAG) to 1600 and 3200 (FLEX)

By combining SDR# with a software package called PDW, these signals can be decoded into their numeric or alphanumeric messages.

There are many users of these systems, and it seems different channels carry generally different traffic. The frequency in use in the image above is 153.275MHz. This is a 1200bd POCSAG signal, with timing/test messages (not decodable) every minute. When there is message traffic, it is generally numeric or simple tone alerting. Likewise its apparent sister frequency 153.250MHz. To the right in the waterfall can be seen 153.325MHz (3600bd FLEX) which seems to carry a lot of machinery telemetry and general 'call so and so' messages, and 153.350MHz, 1200bd POCSAG (CH3), which for me is the easiest and generally busiest frequency. To the left of the waterfall can be seen another FLEX channel, 153.025MHz, this also transmits a very regular timing pulse, as can be seen.

For anyone trying the above software combination, I have found that the following settings work for me - RTL gain 38dB (adjust this on yours to get signal peaks around 30dB above the noise), receiver bandwidth 15kHz, SDR# audio out 54dB.

I have spent quite some time exploring the 153MHz channels, so now will move down to 138MHz and try my hand at decoding those.

On a related note, ive taken the plunge today and purchased a Uniden UBC-125xlt handheld scanner. This isnt to replace my venerable Yupiteru MVT-7100, but instead to add to my capabilities with its 'close call' features. Ive also ordered another R820T2 SDR dongle, and a pair of MCX to BNC pigtail cables, as I intend enclosing the dongles into aluminium boxes to help cut down the noise floor.

A Plug for Bulb...

My energy supplier (electricity and gas) is Bulb Ltd. They run a referral program for new customers.
The link below ive provided for anyone who is considering switching energy suppliers, to take a look and do your own research into them. Take a look at their reviews online as well.

https://bulb.co.uk/

So, your thinking, all well and good, but how does that help your readers save money?

Well, its simple - If you sign up to change your supplier to them, using a link that I will provide below, they give you a £50 initial credit! And, whats even better - they give me one as well!

Heres the link -

bulb.co.uk/refer/martin7906

Numbers Stations

Many years ago, at the height of the Cold War (mid 1980s - not the mid '60s as the press would have it!) , I used to listen to strange broadcasts consisting of spoken groups of numbers. Much later I discovered these 'numbers' stations, existed all over the world, and were government run covert stations, transmitting operational orders to 'agents in place', what the thriller writers would call spies.

Since the fall of the Berlin Wall, these stations have much decreased in number and activity - but they do still exist!

This morning, I have been listening to one named E11 (these names come from the CONET project, that documented these stations), on 7317kHz USB.

The original Enigma and CONET projects no longer exist, however there is still a group that is documenting these stations -

http://priyom.org/

One great aspect of this projects website, is that on the homepage there is a schedule and a 'next station' timer! This makes tuning these stations in very easy - simply tune to the frequency and mode shown for the 'next station' and wait...