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Technical Description (2015)

Introduction

This is a writeup of the technical side of our station. Whilst we have had the fantastic support of the YMCA here in Birkenhead for our studio we have had to supply all the equipment ourselves. In the early days of 2008 when we started we were set up with the help of a grant from Help the Aged which allowed us to buy a secondhand mixing desk and other supporting equipment etc. Our early days used a lot of old PC's etc. but we have been slowly upgrading our systems. We  have built our station on a modest budget mainly using low cost consumer PC's, and so on. Obviously if money was no object we would have done things quite differently.

For our first RSL (Restricted Service Licence) broadcast in 2009 Vintage Radio (VR) had the use of two rooms in the top floor of the YMCA building in Birkenhead. For RSL2 in November 2009 we had the use of the same two rooms. The "studio" was on the top floor and housed the mixing desk, internet streamer and OFCOM recorder and is the centre for the actual broadcasting. Another room was designated our "Green Room" and used for guest reception, off-air programme preparation and monitoring of the transmitted audio by both FM and Internet.

The two rooms were kept in contact by "on screen messaging" - software Yellow Stickies plus two way radios which were used in both “setting up” and “real time”.

The VR studio was built from a range of equipment, some purchased, some loaned from various members of the technical team and the Flame Radio community radio station. The equipment is not brand new and in most cases has seen a lot of use but works and does what we want.

The studio was built and commissioned by our own technical team.

Gordon from the Wirral Amateur Radio group set up the VHF FM transmitter and aerial system that was supplied by Flame Radio. A spare back-up transmitter was made available from 7 Waves.

Now we are at the start of 2015, some 6 years later. We have moved to 7 days a week broadcast of which the 5 week  days are live from our studio. We are now in a single dedicated room in the YMCA at Birkenhead which we previously used as a 'green room' and office whilst on-air with our earlier RSL's. The YMCA Wirral have been extremely supportive to Vintage Radio. We have split the room into a purpose built studio and a office/'green room'. We have been in this new studio since 2012.

How is this all connected together?

Block diagram 2015web smThis is our current studio configuration.  It doesnt include our browser PC's as these are external to our studio network and would only clutter the diagram even more. (Just click on the image to expand it into your screen)

 

 

 

Mixing desk

The mixing desk is a 16 channel Alice Soundtech Series A desk purchased  second hand from ArrowSound hospital radio. We believe it is alice_mixerabout 20 years old and had been unused for a few years by other organisations and required quite a lot of attention to clean up the desk and the audio faders which were electrically very noisy. A number of faders could not be cleaned but we had sufficient channels that worked to make a working desk. The makers of the desk provided us with a user manual with all the circuit diagrams free of charge for which we are very grateful. Unfortunately some of the electronics also required repairing. It was not the latest equipment and despite the odd hiccup has generally generally worked well.

Each channel can be trimmed for level and the microphone channels, of which we had three, had pan controls to get the stereo positioning correct. Currently we broadcast in mono at 64kb/s mp3 although we have just (January 2015) started a trial to move to 128kb/s mono  in mp3 format.

The desk has one main audio bus. In addition there was a monitoring bus that fed into a pair of monitor speakers via an elderly Rotel RA820 audio amplifier  and three sets of headphones for studio presenter and guests connected via a dedicated multi-channel headphone amplifier. The monitor speakers are set to mute when a microphone went live although they will still play the audio from the desk.

We have audio feeds from:

Three microphones

Two CD players with auto start from the desk

IRN news feed (as of April 2010 not used for our internet streaming service)

An audio channel from the RS Player audio jukebox

An auxiliary audio channel to connect laptops etc.

 Source equipment

numark_mp302

Numark MP302 CD 19” rack mounted players, with autostart, triggered by the desk faders going off zero, are used. The fader start electronics was built by our technical team as the desk was incompatible with Numark players. Numark were very helpful and their technical people supplied the circuit diagrams so we could build the interface. We had to make some minor modifications to the circuit as we had some problems with contact bounce from the mixing desk which used a dry relay contact to drive the interface circuit.

In addition to the three studio microphones and an IRN news feed we also use the RS Player jukebox software (http://www.rsplayer.co.uk/standard.htm) running on a Dell Windows 8.1 PC with one audio channel connected via the appropriate desk fader. At the time of writing our experience of it has been very positive.

The main microphone is an Audio Technical large capsule condensor microphone. The two guest microphones are AKG C1000 condensor microphones.

RS Player playout software - audio Juke Box

The audio was from a PC running the RS Player Audio playout software (http://www.rsplayer.co.uk/standard.htm). We looked at a number of packages but this was generally well regarded, easy to use and a fraction of the price of the MYRIAD software. It cost around £70 and the MYRIAD software is several thousand. As we were running on a shoestring it was not a difficult decision. So far all who have used it were very pleased with it even though most presenters had been trained on the MYRIAD system and generally found the familiarisation took a few minutes.

The RS player software runs on a Windows 8.1 Dell PC with a 22” LCD monitor.

The RS Player is a high capacity audio player database that contains copies of thousands of music tracks. Our pre-recorded Vintage Radio tracks and programmes could also be loaded onto the database. The audio was presented to the desk via an individual channel fader. We also created a backup copy of the database on a separate external hard disc.

The RS Player system could also be used for constructing individual play lists of music for individual presenters just like the MYRIAD system. These play lists allowed tracks to be selected and played in sequence or selected from a screen display in any order. These Play lists were very useful as we built a number of them to create programmes for overnight runs when the station was unmanned.

The RS Player also can produce play list logs that may be required for copyright and licensing purposes. As of January 2015 we are looking to trailling Play It Live and also radio DJ (v1.7.x) as an alternative to RS player. As we are a group of volunteers who are largely over 60 tehn ey sight is an issue and an number of our presenters find teh user interface on Rs player not easy to read. White text on black or dark grey is not ideal for people with vusual acuity issues especially if the font and windows sizes on the playout screens cannot be re-sized. 

Audio processing

When transmitting on the radio for RSL's it was important to ensure that the quality of the audio is optimum. This we achieved by compressing the audio feed slightly which had the effect of reducing the high volume peaks and increasing the low volume peaks slightly and adjusting the audio frequency response (a bit like adjusting the treble and bass controls on your Hi-Fi). We use a Triple C multi-band audio processor. On this occasion we also use the built in level limiters on the desk.

We were mindful that adjusting the audio response enhanced the listening experience for the over 50’s and those people who may not necessarily be listening to the programmes on the highest of quality radios. In other words we achieve a compromise. For broadcasting on the internet we use our steraming software to apply some light compression to avoid the heavily compressed sound of some commercial stations. 

For our internet feed we use the audio processing on Radio DJ. We give a small LF and HF boost and add some compression and some limited AGC audio processing.

Transmitter and Aerial (for RSL's only)

Aerial.

We used a transmitter made by the Alice company and purchased from Flame Radio. Due to the OFCOM Restricted Service Licence we were limited to a maximum height above sea level for the aerial and a maximum power of 10 watts. We used a vertically mounted (polarised) folded dipole, with a 10m long (approx.) downlead to the transmitter.

The transmitter and aerial was tuned to give the optimum performance which was very important given that we were restricted to a 10 watts output into an omni-directional vertically polarised aerial. The aerial was borrowed from the 7 Waves Community Radio station and was actually cut to different frequency than the 87.7MHz we are required to transmit on. This meant that the transmission performance we could achieve is slightly less than optimum.

A professional aerial erector installed the transmitter aerial. The transmitter was set-up by a radio engineer to ensure that the power was within the OFCOM licence conditions and that the transmission performance is optimised.

A remote control kill switch is set up so that the transmitter could be ‘killed’ at a moments notice from the studio. A standard wireless remote control mains switch was purchased from a large DIY retailer and found to have an adequate range.

The picture also shows the satellite dish that we used for the IRN news feed.

When we do aour next RSL (when we can afford it) we will be looking at other more efficinet aerial designs to optimise our erp and range.

Radio Coverage for RSL's

map_midBy clicking on this map, it will expand into your screen and show the predicted coverage of the transmission on the allocated frequency of 87.7MHz.

Whilst the Wirral is relatively flat and is not more than a few tens of metres above sea level it does have a sandstone ridge down its spine plus a number of high rise buildings in the Birkenhead area which adversely affected the transmission coverage.

As we indicated previously the transmitter is limited by OFCOM to 10 watts and the aerial was a vertically polarised omni-directional dipole which would give minimal antenna gain. These factors tend to limit the range for a good received signal to around four miles radius of the transmitter. In practice the effects of reflection and other propagation effects enables some listeners as far as Southport to the north and Thornton Hough to the south to hear the transmissions.

Station Failure

For RSL's it was essential that if the audio signal (from the playout system ) or the mixing desk failed, that some form of programme and station identification is still transmitted. We originally borrowed use a piece of equipment from Flame Radio, that detected any gaps in the audio feed from the studio of more than a two to three minutes and then switched over to an pre-corded programme on an MP3 CD player. This then plays some music and station identification at regular intervals. We now have a PC based solution using the Czech software Pira CZ Silence Detector which also has the benefit of being free. It is used on a dedicated Intel Atom based PC running under Windows 8.1 which emails a failure message to the technical team  when silence is detected. We also have a piece of audio switching equipment which we designed and built to switch backup audio to the  transmitter when we are using radio for RSL's.

Internet Streaming

A key requirement of our transmission period on the air was that we also supply a concurrent audio stream over the Internet via our web site. This was important as it allowed Vintage Radio to increase its reach beyond the range of its VHF radio transmission when broadcasting via an RSL, which is approximately a four mile radius of the transmitter – centred on Birkenhead in the Wirral.

We take an audio feed from the studio mixing desk and feed this into a PC dedicated to streaming the audio. The PC - now a Atom base OPC running Windows 8.1uses a Behringer USB sound card to collect the audio from our distribution amplifiers this passes into a BUTT encoder and hence to an ICECASTserver to encode the audio into a mp3 format audio stream ditsributed over our studio LAN. This is then fed to our streaming software (Radio DJ) running on a Dell Windows 7 PC via the studio LAN (where the studio is based) and then out over the internet.

We encode the audio as mono at a bit rate of 64kb/s using mp3 format (although as of January 2015 we are trialling a 128kb/s service) and distribute via a streaming package from our Service Provider that will support a maximum of 100 concurrent listeners. The costs of streaming are dependant on bit rate and the number of concurrent users. We currently use mp3 format encoding. The internet streaming PC is enabled for remote management via Remote Utilities software. Up to January 2015 we used LogMeIn but although this is a truly excellent product we were unable to afford it since they went away from their 'free' offering in 2014. We have only been using Remote Utilities software for a couple of weeks at the time of writing but it is proving to be a excellent product.

The Vintage Radio web site is set up to use a range of  embedded media player to players including TuneIn - which will run on any audio platform.. 

One issue with the Internet streaming was that the audio encoder introduced a considerable delay of up to 30 secs. This is a known issue and can be easily seen on Cable TV systems where the TV and associated audio is supplied via digital systems and when compared side by side with the terrestrial equivalent shows a very noticeable lag between the two sources.

Our streaming service which we started in April 2010 was originally run on RS Player but as of January 2011 is now run from Radio DJ using a dedicated Windows 7 based Dell PC.

Satellite News feed (currently RSL's only)

One of the key requirements was to be able to supply a national news bulletin on the hour from Vintage Radio, This we did by contracting with Independent Radio News (IRN) for the period of the transmission period. They in turn supply the news feed from Sky.

We used the IRN news feed from the Astra satellite located at 28 degs E. We fastened a 60cm satellite dish onto the roof of the YMCA near the transmission aerial and was then fed to a satellite receiver in the machinery room.

The audio was fed to the mixing desk via twin screened audio cable on the outside of the YMCA through the window seals which we had determined had enough “give” with the cable so as not to crush the signal pairs.

As the receiver supplies standard audio (unbalanced) and the mixing desk was balanced input we had to create a simple unbalanced to balanced adapter, which we did  by simply tying one side of the balanced input to earth. We then trimmed the audio level on the desk to ensure the desk audio levels were correct.

Content monitoring

Whilst we are on air we have to monitor our signal continuously so we could ensure we are actually transmitting and that the technical quality of our transmission is acceptable.

Firstly, for RSLs where we broadcast on VHF FM we kept a VHF radio in both our 'green' room and studio at a low background level so that the presenter and studio manager could monitor the signals. It was also a task of the studio manager and the technical support (who were also available at the studio whenever the station was manned during normal broadcasting hours) to check the internet feeds by logging onto the web site and checking the audio was streaming correctly. We also used listener reports as a secondary check. We also encourage all presenters to “keep an eye” on the signal levels on the mixer unit to ensure an adequate audio level.

Secondly, when broadcasting via an OFCOM RSL  we had to comply with their requirements for monitoring which stipulated that all programme content must be recorded and kept for up to 42 days from the last date of transmission. The 42 day recording requirement was met by use of yet another PC that was dedicated to the task and used a specific piece of software that took the audio stream from the transmitter audio feed and recorded it into 60 minute duration, time stamped audio files. The format of these files is mp3.

This also has the secondary benefit of being a source of programmes for subsequent re-transmission for our next RSL and also for people who would like a personal copy of their programmes. However, in practice we are using two PC's, one connected to the desk and one connected to a portable FM radio, basically as a 'belt and braces' approach. Whist we are broadcasting on the internet we use some other software to record all our live output fro archive purposes (in hourly chunks) 

There is no legal obligation to maintain such a record whilst only broadcasting on the Internet. We now use a dedicated Windwos 8.1 based Atom PC running the excellent Play it Recorder software. In turn the files are recorded onto one of our large studio RAID array NAS drives. As part of our cost saving we are forced into using normal 'consumer' or 'small enterprise' systems. We currently use two NAS's. A Buffalo Drivestation running in mirrored RAID and a second Seagte NAS (a Black Armor 220 . The Seagate has been an an absolute nigtmare and is just not reliable.  Since we bought it from new about 3 years ago we are now on our 4th replacement system. The last one working for a month after its replacement before failing.  In fairness to Seagate they have extended our warranty period to far in excess of the original time frame but  the Black Armor 220 has just not been reliable. Its replacements have always been re-furbished drives. So we are unable to recommend Seagate NAS drives - at least not the Black Armor 220. We are using NAS's with modern 2TB drives but the failures appear to be drive based. All power to our NAs's goes via APC UPS 's so the power is conditioned and stabilised before powering the NA's.

Communication with the outside world.

Dedicated Phone number

In addition we wanted to post a publicly accessible telephone local style telephone number on our website. We use the free SIPgate VOIP system and set it up with a small amount of credit to allow outgoing calls. SIPgate gives considerable flexibility as to choice of telephone numbers and we were able to select a Liverpool area 0151 series number. We connected a DECT cordless phone via an ATA box which had an ethernet network interface which was then connected over the YMCA network.

Dedicated e-mail facility

We also offer an e-mail facility whereby listeners could e-mail in their requests and comments. The inbox for the mail system is received from the Internet in the Studio and displayed on a large screen monitor (22")  so that the current announcer can address the requests and comments. Web mail is used so we could view the emails from both studio and Green room PC's.

Networking

We had networking requirement and needed to create a studio LAN which was to connect the back office systems together and provide a network infra structure for communication PC's plus the streaming PC and the SIPGate phone via the YMCA network. We have about 8 PC's for various tasks and two RAID arrays, The browser PC's are kept outside of the studio LAN and the remaining PC's are segregated using VLANS depending on their function. We also use a enterprise standard content aware router and firewall device to sit outside of our studio LAN.

Computing

We have currently 8 PC's:

Two of these are elderly Dell PC's running Linux MINT  (previously runningWindows  XP) and are used solely for browsing and checking emails in the studio.

One is running Windows 7

The remainder are running Windows 8.1. We have configured these so they boot into the desktiop and we also run Classic Powershell on them to give  start button back. Three of the  PC's are running Atom processors as we have found that Windows 8.1 runs better than Win 7 on low powered machines. Ours are the early first version Atoms rather than the latest Intel Bay Trail quad core versions. We tend to keep these machines as single function - Encoder, Silence Detector and recorder. We did have one problem on the two Asus Netttop Atom's running Windows 8.1 where we found that under certain circumstances we were running out of CPU power and getting 100% CPU occupancy. This we traced to the USB mouse function. If we left it alone the CPU occupancy dropped right back. These two systems tend to run around 50% occupancy on average.

Health and Safety

Whilst not operating a fully funded commercial station with paid staff it was important that we operate to the highest possible professional standards and hence it was essential that we had to consider the aspects of health and safety. A risk assessment was undertaken before going on-air to identify potential issues and hazards and made available to our hosts, the YMCA.

In addition appropriate insurance cover is in place to protect studio staff and guests and their belongings and all studio equipment.

Documentation

A number of documents were written for station staff covering topics such as using the IRN news feed, operation of our two way radios used for communications between studio manager and technical support etc. These are laminated and kept in the studio.

Some newish stuff!

To increase the flexibility of content the technical team are working on a number of projects designed to increase our flexibility in respect of content and a wider embrace of members of the community that may not be able to make the studio in person.

1. An “outside broadcast” unit already constructed by one of our team that will allow “round the table” interviews with live transmission into the studio via the mobile internet facility. Completed and all fits in a small briefcase. Currently being used for off-site recordings where a simple digital recorder gives insufficient flexibility. We have (January 2011) changed our streaming software to use Radio DJ - a free station automation package. This allows us to switch as specific times to a external Internet stream. We are investigating how this may allow us to have live broadcasting from remote locations.

2. Creation of a secure content archive and database. This allows us to use appropriate previously recorded material if we have a unavoidable shortfall - e.g. a presenter falls ill etc. We now have a set of 'emergency' programmes which are hsoted on our studio playout system The content archive has been built and all streamed and non-streamed content is backed up to a set of RAID network storage systems. In addition we keep another copy of our content off-site. At the time of writing our non live day streamed content is archived on our Dropbox account now that it will support 1TB but we also secure a copy on local USB hard drives off-site. We have some limited  file storage on one of our NAS's.

Internet Streaming

As we are not in a position to broadcast on the airwaves (87.7MHz VHF FM), for a number of reasons, primarily financial as well as regulatory - no frequnecies are spare fro community radio on the VHF FM bands in the north west of England, we decided that we would put together a internet based service (see our News and Schedules pages for more details) so we could maintain our broadcast presence for our growing listener base and also continue to give an outlet for all our broadcasters and producers.

Our content for this service is a mix of mostly live as well as pre-recorded (wekends only) programming. A traditional studio approach was not required. So we decided to design a virtual studio. This used a PC acting as a streaming server located in the YMCA to which we could upload remotely all our content. Click on Internet Service block diagramthe thumbnail to see a block diagram of our solution.

We are streaming using mp3 format and at bit rate of 64kb/s in mono.(determined solely by cost). We now use the Edcast 3 encoder - no longer available from the web site as of January 2011). The reason for streaming at this bit rate was solely driven by the cost of the streaming service. 

As of 2013 our streaming server is now an Windows 7 based Dell PC running on a Intel Celeron processor. It runs at around 11+% occupancy on average compared to around 30%+ when we ran the same software on an Atom processor. As of late 2014 we now use Simplecast encoder rather than EDCAST. This allows us to support multiple streams e.g. 64 kb/s plus our trial 128kb/s  service.

In 2013 we replaced RS Player in our internet streaming system with Radio DJ (http://www.radiodj.ro/) which is a lot more flexible for this function. It allows us to stream files of any size and arrange them in any order by creating  daily playlists which can be edited on-line. In addition it allows us to stream live feeds from our studio as we do on our Live Days (as of We stream live programmes from our studio on five days a week from 8am to around 10pm, although some days it is a little earlier. 

We have networked  our  streaming server to allow secure remote access  to set up the weekly schedules and we now transfer all programme files using DropBox a cloud based storage solution. We use both the free and paid for DropBox service and use of this cloud based storage system has allowed us  create a virtual network to move our programme files around without having to drive all over the Wirral to collect CD's and memory sticks which we had to do when we first started.  Needless to say we soon changed that. We consider ourselves hence a very 'green' organisation. These packages (LogMeIn and dropbxox) allow us to control the studio and move files to the studio without the need to visit it physically. We were until earlier this month using remote access via LogMeIn to remotely access our internet streamer, set up the weekly schedules etc..  We now use Remote Utilities software for remote network access, this is free for up to 10 PC's. Hence for organisatiions such as ours which have challenging finances this seems to be excellent. it seems to be a stable software package, albeit slightly more copmplicated to set up than LogMein. We also looked at Team Viewer but its licence conditions meant that we were legally unable to use this package.

The Future

Our next major expenditure is to replace our mixing desk. Our desk is still working but is showing signs of its age. We would like to purchase a Sonifex S1 desk but at approximately  £3000 this is outside of our budget. So if anyone would like to make a donation to Vintage Radio to allow us to buy a new broadcast desk - preferably one of these we would be very grateful. What else is on our wish list?  Replacement of our two elderly PC's we use for browsing. A new studio monitor amplifier (ours is at least 20 years old).  A replacement for our Seagate NAS drive would be useful - one we can rely on and prefereably one that uses Western Digital or Toshiba hard drives.