Our power company needs to do work on one of the two feeders coming up to the tower, so they want to switch it off and let us run on the other feeder. We had meetings and they agreed to bring up generators (well sound insulated ones) to replace the missing feeder for the few days they are working. Thats good news for me because unlike everyone else at the tower I only have a connection to one of the services, the one they want to take down.
So I have to go off for an hour while they hook up the generator and again when they disconnect it, much better than a few days of being down.
The power company told us they were going to do a test on that feeder before the work but that it would not affect us, okay.
Thursday service 2 went down. I got a call from the boss telling me we were off the air, I was picking up my son from school so I collected him and we went to the tower. As I pulled into the parking lot I got a call from the power company telling me it was them, the feeder was down and they were working on it.Okay, at least it was not me.
Now we had our test, all stations were running on service 1 and it held just fine. We had scheduled a test to put everyone on service 1 on an upcoming night but now maybe we don’t need to. In an hour power was back and my trusty Thomson DCX Millennium came back on it’s own, with me pushing any buttons. The video servers where another thing.
I like it when it’s not my fault.
After the boss’ call about being off the air I got a call from U-verse asking what was wrong, they’re very good at letting me know I’m off the air. After I was on my way home I got another call from them, I always know it’s them, there’s no one else in Kansas that calls me. This time they let me know I was missing one channel of audio. So I turned around, after dropping my son off at home and came back up.
I could see one channel was low, tried switching the master control switcher to exercise the contacts but that did not do it. Checked the encoder, it seemed fine. Then I switched the Left – Right inputs to the Audio Encoder and the channels were balanced, I switched them back and still they were good. No idea what that was.
Now we had pictures and two channels of audio. I went home.
So my flashing lights project hit a snag, when I sent an on command to the IP IO 8 box the flashing lights turned on but most times when I sent an off command they stayed on. During the testing phase everything worked well. I turned them on and off with commands from the GUI web interface and from a companion box, the lights came on and went off.
But now that they were built, inside a stainless steel with wired together with fuses and terminal blocks, the relay built into the IP IO-8 box seemed to stick on, even powering it off did not make the contact open. We found that an external octal socket 24 volt relay would do the trick, the built in relay would reliably control it and in turn the flashing lights came on and went off like they should.
The power supply as checked, it produced 5 volts @ 4 Amps and 24 volts @ 1.4 Amps. The flashing lights should have pulled about 1.2 Amps, so this should have been alright. The 5 Volts was for powering the IP IP-8 box and in the original tests I used it’s wall wart to power it, not this supply. Now it seemed strange that during these tests on the completed boxes when using the GUI web interface after each click we had to log in again, I did not remember that from initial tests at all. So we checked the 5 Volt supply, we hung a scope on it and watched.
1/2 ohm resistor
There it was, the 5 Volts was being sucked down by the current draw of the lights, it dipped far enough to cause the IP IO-8 to reboot. But why was that? The 5Volts has several Amps available to it and the little box draws way less than an Amp of current. This is a switching supply, it adjusts it’s switching frequency to follow the current drawn from it, but the 5 Volts and the 24 Volts are tied together. When the 24 is sucked down by a large current demand the 5 Volts is sucked down with it. Thats my guess!
But the flashing lights should be within the current range of the power supply, is it just too fast and the supply can’t keep up? But switching supplies operate at hundreds of kilohertz,
IP IO8 with GUI
how could a switch on and stay on be too fast?
Now the flashing lights are large LED flashers from Federal, their like what you find on top of old police cars. They are rated for 0.4 Amps or 0.17 Amps average. I am running three of them for a total of 0.51 Amps Average, or 1.2 Amps total. The average is used because they have their own internal flash circuitry, so the current must pulse with the LEDs.
The relays were staying latched and the only way they could do that was if they were fused together. But why would just 1.4 Amps @ 24 Volts do that? We needed more data!
So we measured the current, now we had done that already using a DVM and it’s peak hold function and it had read out about 1 Amp. Now I said lets use a resistor and the scope to me sure current so we can see any spikes. And thats what we did.
At first we just looked around and found a 10 Ω @ 1W and put it in series with the 24 Volts and then put the scope probes across it. And this is what we saw -
10Ω that changed to 26Ω
Thats a 15 Volt drop across the 10Ω resistor, with E over R that equals out to be 1.5 Amps, just about what I thought it should be. The resister got hot and changed values so we hunted around the found a really nice 0.5Ω at 60 Watts. We tried again, now I read 500 mV across a 0.5Ω resistor which equals 1 Amp. This was better as this was closer to what I expected and well within perimeters.
Take a look at the video above, of the voltage drop across the resistor, did you see it? That spike right at the beginning, that was our clue, right there.
I thought it might be the big external relay turning on so we put the relay on the other side of the resister and still we got the spike.
Marty set up the scope (he was very good at that) and we captured the spike.
As you can see the spike goes off the top of the screen. Now Marty really caught it and we got a closer look at it.
Voltage Drop across a 0.5Ω Resistor
This was why the 5 volts took a dip at turn on and why the internal relays fused and stayed on. No where in the papers on the big LED flashers did they mention this extreme high current spike at turn on, maybe they don’t even know about it. We think it could be from it’s own DC to DC converter that shows a direct short as it turns on. A single LED Flasher shows a smaller spike but still draws about 8 Amps.
So we are getting a bigger power supply, instead of 1.4 Amps the new one will have 5.8 Amps @ 24 Volts. I hope that will solve this problem, along with the external relay to handle the current. Though I still don’t get why it all worked so well when it was tested before?
First it was a Broadcasters Breakfast with ERI, they laid out a really nice setting and then got down to business. They had the story of KJAV and the new Chief who found the tower about ready to fall. ERI worked with the station to take down the old one and put up a new one in just a few weeks. They showed video of how different tower are taken down with controlled falls and how they make sure the TX building is not damaged. Very interesting.
Then I went by their booth and asked if they would help with a video I am thinking of on guyed towers. They were very cooperative and I hope to use ERI to make sure I don’t make any mistakes in the tutorial.
Later in the day a seminar about Cel Phone ENG. I know they have been doing this for at least a year or two now but it has really grown now. They talked of a news piece covered by ABC with both a Truck and a Cell Pack and when it started sooner than expected the Truck was not ready and it was covered with just a Cel Pack. Other events have been covered on moving trains even.
The 3G networks can be hard to get thru as more and more smart phones are used and latency is a problem, thats why multiple cel phone network adapters are used (lots of Rabbit Ears as I call them). But even with 4G it will fill up too. Even with great compression it’s still a lot of data to move over something designed to get you your Google map or update your phone Apps. They see a combination of Cel Networks and WiFi as an answer when the system can use both at the same time to off load some of the data. Panasonic is even working on a ENG camera with LTE networking built right in.
One company, TVU, is working on a backpack with both Cel Network connectivity and ASI out to feed a remote truck so both can be used as needed.
Stopped by the FEMA booth and they had a little model of a Primary Entry Point facility. Very interesting and something I will go into more detail later on.
I met Steve Mareen of RF Specialties Group over at the Hitachi / Linear booth where I met the guy who is going to setup one of their exciters at my transmitter next week. They want to show it off working on a real high powered transmitter and I agreed to let them do in. They tell me it should take all of 1/2 hour to get it going. I will report on this next week.
Before that I was over at the Thomson booth and talked with Michael Roosa our salesman and Richarad Fiore Director of Transmission & Mobility about their new exciter the ATSC 8000 which I was told the story of a station that wanted to increase it’s power level from 40KW to 50KW as I recall but pushing the tube that much made correction so difficult that after several exciters were tried only the ATSC 8000 had the correction range to get the job done.
I walked over to TeraDek and saw how small they make the SDI to Cel Network adapters now little bigger than a paperback book. They also make one that uses WiFi to stream to a local laptop or to iPads for remote monitoring. Pretty cool.
Time to get out to the show for an early start on the last day and then it’s back home.
We are putting in a couple of new waring systems to alert personnel to unusual conditions. We have built the two of them inside one box and they share a common power supply of 12 volts. Each is operated by a 12 volt relay but we have also installed a manual bypass so we can turn the lights on by hand.
The lights are installed all around the building and in the parking lot. Each is wired as a home run back to the terminal blocks and is fused independently. That way a short in any one line will not take the system down.
Some of the lights are the ones you saw on this blog flashing not too long ago while the others are smaller version.
We are looking at using an iPad to display data while on the tower, to do this we would need a wired network connection since a wireless network won’t (may not ) work. But I cannot find any adapters to allow a wired network connection for the iPad. It seems that the common solution is to use a pocket wireless router that plugs into the RJ45 and provides a wireless network for you. The iPad to USB adapter will not work with a USB to Ethernet adapter as I have read, so thats out.
The reason for this is FileMaker Go, it’s an App that lets us access a FileMaker Pro file on your iPad or iPhone. I created a data base in File Maker to keep track of all the antenna and cables on the tower, it uses seven data bases to contain all the data. If the iPad is on the same network as a computer with the data base on it can be accessed on the iPad. If not, you can load the the files on to the iPad or iPhone and then you can load the changes back to the computer based data base.
The reason for all this is so I can go put the tower and compare the data base with whats really up there.
So it’s standard procedure before going up the tower to take a radio with you and to check that it’s operating correctly. Last week I was going up the tower to check on some new dishes that had gone up and put our ID tags on a couple of new racks. Recently I was assigned my own radio which sits on my desk in a charger. I got a hand mic/speaker to go with it so I don’t have to un-clip it to talk. So in the mornings I turn it on and hear it squeal, so I know its working, and incase the boss calls for me.
So I’m going up the tower and it occurs to me to do a radio check, but I figure, What the Hell, I heard it this morning and I go to second level. When I get up there I leave the elevator door open, I know this won’t take too long, and I go on my merry way. I’m up on the catwalk, walking carefully, with one hand on the rail (you can see through the grating to the ground 200′ below), when I hear a voice calling me from below. That’s strange, if they want me they would call me on the radio.
But now I hear it again and it’s one of the riggers calling my name and now the call bell for the elevator is ringing. I try to call them on the radio but don’t hear anything back. So I hurry up and do what needs to be done and get back in the elevator and go on down.
When I get down Dave’s waiting for me and we test the radio, it transmits but you don’t hear anything on receive. I pull the detachable mic’s connector and the radio’s speaker works fine. The Mic/Speaker had failed. It had worked this morning, I worked the connector but never got anything out of it. So I replaced it and the new one works fine.
Moral of the story, always do a Radio Check before going up the tower!
Aqua Tek is a new iPhone case made for engineers on the go, and anyone else who has an active life style. It has a solar cell back that recharges the internal battery that doubles the battery time of the iPhone’s internal battery. It’s water proof so you can swim with it and still operate it’s touch screen. It should be on sale soon as they have exceeded their funding goal on KickStarter.com.
I am a proud member of SBE Chapter 40 in San Francisco, even if I don’t attend many of the meetings. But I was at the latest meeting the other day and I am glad I was there to hear what was said. A couple of members told us what they found in the “Middle Class Tax Relief and Job Creation Act of 2012″ or its official name HR3630.
It seem a couple of extras were thrown in at the last-minute. The one closest to Broadcasters hearts is a small provision in SEC. 6409 WIRELESS FACILITIES DEPLOYMENT. This prevents local governments from denying modifications to wireless towers (i.e. Broadcast Towers) that ”does not substantially change the physical dimensions of such tower“. So, if you want to add as side mount antenna or a dish it would seem you can’t be denied, Federal law supersedes all others. This provision states that it applies to “ (A) collocation of new transmission equipment; (B) removal of transmission equipment; or (C) replacement of transmission equipment”. This would seem to make life a little easier when tower changes are needed. See your FCC lawyer for details.
Another little item is SEC. 6408. ”STUDY ON RECEIVER PERFORMANCE AND SPECTRUM EFFICIENCY”. This sounds like it pertains to DTV receivers or some such but it’s real goal is to keep LightSquared alive. It states;
“The Comptroller General of the United States shall conduct a study to consider efforts to ensure that each transmission system is designed and operated so that reasonable use of adjacent spectrum does not excessively impair the functioning of such system.”
As you might have read recently that LightSquared was shot out of the water by poorly designed GPS equipment what would have received the LightSquared signals (that are within their purchased band) and interfered with their operation. Instead of fixing the GPS equipment that operated outside of the GPS band LightSquared was told they can’t use the spectrum they purchased. This seems to be an end run around the FCC ruling to get the Comptroller General to do it’s own test to make sure the offending GPS receivers stay within their own band. The good thing for Broadcasters is that LightSquared offers wireless data service without using any Broadcast Spectrum, more power to them.
Another item caught my eye and that was, SEC. 6407. GUARD BANDS AND UNLICENSED USE. It seems to say that the guard bands between licensed bands can have unlicensed users in them. If it’s a guard band why would they allow anyone in there?
The resisters are under the light pipes on the left
Those little IP I/O boxes I have been testing are working like a charm. I have four of them in my office to test, one is the master turning on relays in three others. The plan is to have the remote boxes switch 24 volts to turn on warning lights and to feed back to the same boxes input, that one will go to a fifth box that will show the remote box has 24 volts and switched. Pretty cool.
Normally the inputs just require a contact closure but they will take in up to 30 volts. To do this I need to cut out the pull up resisters.
I am working on a project that requires three flashing lights in several places. We got these LED flashers that have different programable flash rates and I wanted to see how they worked so I hooked them up to see.
The lights flash at different rates and in a random pattern, I am told this is to keep people from going into epileptic fits from a regular Flash-Flash-Flash pattern. If you have noticed even the police and ambulance lights are a random pattern these days. I know that in this video they look more like they are flashing together but in reality they are not, it must be the frame rate of the video that makes it look like that.
To control them I am using an IP Relay/input device. We can control them from a web browser or they can talk to one another. More on this later.
One of the station's IOTs failed and when it was cut open (by the Mfg) they found two of the grid bars pealed away causing a short. Pix soonAs of - 2 days ago
Added fifth encoder to our stat Mux. Needed help and some experimentation but Kelly and I did it. Now his KPOP channel is on the airAs of - 3 days ago
http://t.co/NiUBKO3e was down for a good part of the day due to Network Solutions problems. Fixed now site is back upAs of - 3 days ago
My Thomson DCX came right up by its self. It's very reliable. Matco server powered up but would not start automation Pgm. Had to reboot, ok.As of - 1 week ago
Got a call about 3 saying the TX was down. As I got there PG&E called telling me they were down. Glad I wasn't me. About 1 hr later we're upAs of - 1 week ago
TheOnLineEngineer.org is all about Broadcast Engineering, from Transmitters and Antennas to Video Servers, DAs, TSoIP, and Video Paths just to name a few. We cover it all, Drawing upon my 35 years experience in broadcast television I share my knowledge with others and welcome any input or question from other engineers or students of broadcasting.
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Our power company needs to do work on one of the two feeders coming up to the tower, so they want to switch it off and let us run on the other feeder. We had meetings and they agreed to bring up generators (well sound insulated ones) to replace the missing feeder for the few days they are working. Thats good news for me because unlike everyone else at the tower I only have a connection to one of the services, the one they want to take down.
