Technical

A Tale of Two Tielines

Welcome to our Technical Pages | Our Studios | A Tale of Two Tielines | Our Transmitter

 

Have you ever wondered how our 96.5 Inner FM programs get from our studios at the Warringal Shopping Centre up to our transmitter site at the Austin Hospital? Did you know that there were some amazing technical dramas in play behind the scenes that could have easily kept 96.5 Inner FM off the air for five months?

Adrian Hook writes:

Here at 96.5 Inner FM (3INR) we have much to be thankful for - generally, but most particularly to a couple of pieces of equipment made by WA-based company Tieline. Here's why:

For years, we had dreamed of owning Tieline Outside Broadcast equipment for use on the over 40 Outside Broadcasts we conduct annually, the majority being for our VAFA football broadcasts. This very clever equipment effectively takes a digital signal at source, say at the outside broadcast site, converts it to analogue for passage down a normal telephone line, then converts it back to digital at the studio end then through the transmitter to you the listener. The result is almost studio quality sound from a plain old telephone line. Brilliant!

What had always prevented us from purchasing some of this equipment was the cost (over $15,000) which was prohibitive so we soldiered on as best we could with our venerable (Melbourne produced) McCubbin RTL analogue equipment, aided and abetted by some technical gizmos dreamed up by our brilliant techie, Tim Armstrong to get the best possible sound quality over a normal telephone line.

In 2008, however, salvation came to Inner FM in the form of our local East Ivanhoe Community Bank Branch of the Bendigo Bank (with whom we bank, of course) who provided the station with a $10,000 Community Grant, thus enabling the station to find the remaining, more managable amount, to finally get our hands on the much-coveted Tieline G3 equipment. We used it almost from the day it arrived for Street Festivals, Community events and all last years VAFA Football broadcasts and the sound was just great - at long last, we could play music from an O/B site without it sounding like being stuck "On Hold" on the telephone.

A cloud was forming on the horizon, however, which at the time, we didn't realise just how potentially damaging it could be to the station. Since being granted our fulltime broadcast licence in December 1990, we had used the Telstra Analogue Audio Network for our studio-to-transmitter link. Early in 2009, Telstra announced that the service would be withdrawn in November 2009. In it's place, Telstra offered the station what was, in effect, a broadband link over the internet at almost four times the cost of our current monthly rental. Over time, it would send the station broke so we declined the offer and went looking for an alternative - a UHF radio based studio-to-transmitter (STL) link, as used by most Community broadcasters in Australia.

The studios of Inner FM have been located in Warringal Shopping Centre in Heidelberg, Melbourne since 1988, when we were just test broadcasting prior to being granted a licence. We are still there thanks to the generosity and wisdom of successive owners. Our transmitter and radio mast are located in (and on) the Boiler House at the Austin Hospital complex about a kilometre away, as the crow flies and despite the construction of the wonderful "New" Austin Hospital on the site a couple of years ago, we still retained line-of-site, necessary for the effective operation of an STL in which the antennas are pointed at each other, just!

We approached Centre Management at the shopping centre and Austin management who both gave us in-principle approval to mount a yagi-type antenna, about the same size as a normal TV aerial which we thought would do the job at each location, but upon applying to the Australian Communications and Media Authority (ACMA) for a licence for the proposed STL we were informed that due to the proximity to the Melbourne CBD and the congested airwaves in the area, we would have to use much larger and heavier Grid Parabolic type antennas instead. At two metres in diameter and weighing in at 35 kilos (not including their mounting structures) this raised a whole lot of new, additional engineering questions which would have to be addressed.


Warringal Shopping Centre STL Polar GA20-08 grid parabolic antenna

So, we had to go back to the shopping centre and hospital managements telling them that we were now looking at locating much larger antennas on their premises. To complicate matters further, Warringal Shopping Centre had just been sold so we were now dealing with people who neither knew anything about Inner FM let alone their request to plonk a big piece of metal on their pristine roof! Whilst on top of the Boiler House at the Austin, which frequently experiences wind gusts of in excess of 100 k.p.h, their Engineering Department were asking how we intended to stop the antenna blowing away. Good question.....


Austin Hospital STL Polar GA20-08 grid parabolic antenna


Another view of the Austin Hospital STL antenna

Very fortunately for Inner FM, the new Centre Management at Warringal led by Centre Manager, David Knell, along with the Centre’s owner have not only been incredibly supportive of the continued presence of the radio station at Warringal but were also receptive to our request to locate the antenna on the roof as well as in a position which guaranteed line-of-site to the antenna on the Boiler House at the Austin. At this point we need to acknowledge the work of the station’s rigger, Phil Peacock, who had been engaged to install the antennas. Using his vast experience, Phil prepared, on behalf of the station, a set of very precise installation plans and solutions for both locations which met all concerns raised. Phil is something of a doyen amongst riggers in Victoria. He installed our current radio mast on the Boiler House roof back in 1999 which has run without a glitch ever since. In recent times, Phil has been working flat out for the State Government and CFA installing communication facilities across the State in response to findings and recommendations from the Black Saturday Bushfire Enquiry, so we have been very grateful for his input as without it, the job would not have been allowed to proceed.

However, back to November 2009 - just a matter of days before Telstra were due to switch off the Analogue Audio Network and we had no alternative means of getting our signal from the studio to transmitter. Things looked very grim indeed...... until, that is, our technician, Tim Armstrong, mentioned that there was an emergency telephone located a matter of metres away from the transmitter at the top of the Boiler House at the Austin. We approached hospital management again and without actually begging, we asked if we could "borrow" their emergency phone line till such time as the radio STL was installed. To their eternal credit, Austin management agreed and together with our Tieline equipment, was adapted and employed to provide the station with a broadcast service for a few days.........


Austin Hospital boiler house emergency telephone

Well, a few days turned into almost FIVE MONTHS!! We finally switched over to the radio STL at about 3:00 p.m. on Friday, 16th April. For almost five months our Tieline Commander G3 Studio Rack unit and i-mix G3 Mixer worked 24/7 using a humble internal phone extension carrying our studio signal to the transmitter and it never let us down. When the hospital phone system would reset itself every morning around 3 a.m., the tieline just automatically re-dialed and re-established the link  -  for five months!! And, over the summer, that transmitter room at the Austin Boiler House gets very, very hot (over 40 degrees sometimes) but it was nothing the i-mix G3 mixer couldn't handle. Truly, this was service above and beyond the call of duty and we thought that credit should be given where credit is due: without our Tieline equipment (and the conveniently placed phone line, of course) we would have been up the Swanee without the proverbial paddle, so we have a lot to thank the clever people at Tieline for producing such brilliant, hardy, reliable equipment not only for our O/Bs but also for simply keeping us on air – for five months, non stop.

We would also like to take this opportunity to thank John Heselev and John Wilkinson and their staff at the Austin for their continued support and assistance in allowing the station to bolt the antenna to the wall of the Boiler House, not to mention granting us use of their emergency phone for “a few days”, a number which blew out to something like 150 at the final count. And let’s not forget that for over twenty years, the Austin and Repatriation Hospitals have been the location of our radio masts and have been such great supporters of the station since its inception. So, quite apart from being one of the finest public hospitals in the country, the Austin is also the station’s oldest and perhaps most valued friends.

Our thanks also to our wonderful technician, Tim Armstrong and his great crew of helpers: Struan McGregor, Daniele Magarelli and John Pedder for keeping the station on air during what has been a difficult period and for ensuring that the new STL equipment is working to it’s optimum potential, which it appears to be. In fact, the station has never sounded so good. So here’s to another twenty years of un-interrupted broadcasting using our new UHF radio STL and thanks again to Tieline for allowing the show to go on whilst the STL was installed.


Our brilliant technician Tim Armstrong (right) with two of his
helpers Daniele Magarelli (left) and Struan McGregor (centre)