Replacing Harris Aurora 5800 Lan/T1 radio

Gotta watch those Fresnel zones!
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kcbooboo
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Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Wed Jan 07, 2015 7:12 pm

One site I tend to has some dead Harris Aurora 5800 radios. Each is feeding a fairly large (3-5ft diameter) Andrew antenna with 1/2 inch Andrew Heliax. The one at the TX site is up about 450 ft, and is another 100 ft from the building, so there's a very long coax run. I'm surprised it worked, but it did work fine until the radios died.

Does anyone know of a solution (new radios) that will work with an existing Andrew parabolic dish antenna and 550 ft of coax? Most of the new stuff today is totally self-contained at the dish, and has 300 ft network cable limitations. We need something that sits in the building, has its own combiner, and can feed a remote unpowered antenna.

I checked with Moseley: they have a system that puts an up/down converter up at the dish antenna, but that too has a coax length limitation. Some units, such as those sold by Ubiquity, use two short coax jumpers from the radio that mounts to their own dish. They won't work with an existing coax-fed antenna.

They need the height to clear some mountains and trees, and right now the trees are interfering with the Fresnel zone as it is.

Suggested solutions that would use the existing Andrew dish?

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by dbuckley » Wed Jan 07, 2015 9:53 pm

kcbooboo wrote:Most of the new stuff today is totally self-contained at the dish, and has 300 ft network cable limitations.
The 100m limit can be worked around, two ways are either to have a switch as a repeater every 100m, or go fibre, which with single mode fibre can take you 20KM in one hop. Fibre is particularly attractive as it is RF proof, just meaning the that self-contained dish arrangement needs a local power supply, which is a solved problem.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Thu Jan 08, 2015 5:35 am

They're trying to avoid a tower crew by connecting to the end of the 1/2 inch Heliax cable going to the existing microwave dish. Yes, there's a lot of line loss, but it was working fine.

Also, adding repeaters or hubs halfway up the tower also means running power to them, unless they can utilize POE. Even with fiber for the data, a dish-mounted radio still needs power. They're trying to avoid any electronics mounted on the antenna or tower.

I was thinking they might be able to put a reflector up on the tower in place of the dish, and use something like a Ubiquity unit down at the bottom of the tower pointing up (with a radome). Then the network cable run is only 100 feet. But I'm not sure this works well at 5.8 GHz.

Bob M.

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kkiddkkidd
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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kkiddkkidd » Thu Jan 08, 2015 9:07 am

I don't have any idea if it would work but you could try a high power Ubiquity Bullet M5HP. I don't know if you would have any power left at the dish but it would be cheap and simple to try at least. Around $100 per radio. The Bullets have a male Type N connector.

There are also WIFI amps on the market that supposedly put out a couple of watts. I haven't tried any of them.

Although it would require a tower crew, I would also consider using a UBNT radio (Rocket, etc) up at the dish location as an AP and another on the ground as a client in addition to the far end client. Power for the UBNT could be run up the existing coax since no data would be transported via the cable.

We are doing something similar on an AM tower here. I think that we talked about that system here as we were working on it. We are using outdoor CAT5 for the power run but all data is transported on the wifi. The ground client is almost straight down from the AP up on the tower. Being off axis doesn't seem to affect it's operation. I would assume that if we were really stretching the bandwidth it might not be 100% but we are only running a couple of audio streams over it.

Good luck.
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kcbooboo
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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Thu Jan 08, 2015 2:16 pm

I didn't notice any UBNT products that had just one antenna connector; most had two and expected to be mounted behind their dish. I'll look again.

The problem with mounting the whole shebang up at the 450ft level is the need for a network repeater somewhere on the tower, which also needs power of some sort. There's no power available. If they put something up around the 300ft level the path might not clear the hills that are in the way. The other end is at about 100ft ASL. There's a 600ft bump rather close to the low end that the existing path barely clears to the antenna on the tower at 1100ft ASL. The signal barely made it during the summer; we suspect Fresnel zone interference because the tower guys can SEE the dishes from each end.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Thu Jan 08, 2015 2:42 pm

I did check out the Bullet-M and it might just do the job. It could be installed at the dish at one end where the distance is about 75 feet. The one that's up 400ft on the tower could be connected to the Male-N connector at the end of the coax where the Harris Aurora was fed from. I didn't see any examples of coax between the Bullet and antenna; obviously the line loss is going to be a real problem, but surprisingly it worked quite well with the Harris units. Maybe they're a whole lot more sensitive.

I passed the info along. Thanks for the pointer.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Wed Jan 21, 2015 5:52 am

The station bought a pair of Ubiquity Bullet-M units, plugged them in, configured them for DHCP, and got a received signal level of -73dBm, very close to the predicted value. Both the studio and transmitter equipment seemed to be quite happy with the setup and everything is working just as it did with the Auroras.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kkiddkkidd » Wed Jan 21, 2015 7:28 am

kcbooboo wrote:The station bought a pair of Ubiquity Bullet-M units, plugged them in, configured them for DHCP, and got a received signal level of -73dBm, very close to the predicted value. Both the studio and transmitter equipment seemed to be quite happy with the setup and everything is working just as it did with the Auroras.

Bob M.

Cool. For a total cost of $200ish... What did the original Aurora radios cost?

I have found that most of the UBNT stuff works good down to about -75 and starts having problems at about -80.

Later,
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Kevin C. Kidd CSRE/AMD
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http://www.amgroundsystems.com
KK Broadcast Engineering
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kcbooboo
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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Wed Jan 21, 2015 3:14 pm

I think the Auroras cost between $6000 and $8000, and getting one repaired could cost nearly that much.

Right now there's a stack of five bad units. We can't tell if they're not receiving or not transmitting. The only indication is that the receiver isn't getting a signal; the transmitter fault indicators are not lit but that still doesn't mean that they're actually transmitting.

It would be great if one of the Ubiquiti units was compatible with the Aurora enough to see whether the TX or RX isn't working, but besides channel frequencies I'm sure the data protocol is quite different.

I just have no test equipment that goes past 3 GHz.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by Xenirad » Mon Jan 26, 2015 3:38 pm

I have several Ubiquity Bullet M5TI radios in service and they work very well. They are single connector but you still have the problem of length as the 450 feet exceeds the limitations of the POE over CAT 6. You will need to have the power inserter at the base of the tower then you can make it work. Your signal levels will increase dramatically without the 27 plus DB of loss over the coax.
Fred Francis, Owner Xenirad Broadcast Engineering http://www.xenirad.com

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Mon Jan 26, 2015 4:45 pm

The Bullet M5 units normally mount up at the antennas and you run a network cable with POE where you need it.

In this case one antenna was up at the 450ft level of the tower so it was not possible to install the Bullet M5 up there. It was connected inside the building to the existing coax. The network cable was only a few feet so POE was not a problem. If power was available on the tower and a tower crew would climb for free, then they could have gone with other solutions, but the Bullet M5 down in the building is working quite well and that's where it will remain.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by Xenirad » Wed Jan 28, 2015 10:10 pm

kcbooboo wrote:The Bullet M5 units normally mount up at the antennas and you run a network cable with POE where you need it.

In this case one antenna was up at the 450ft level of the tower so it was not possible to install the Bullet M5 up there. It was connected inside the building to the existing coax. The network cable was only a few feet so POE was not a problem. If power was available on the tower and a tower crew would climb for free, then they could have gone with other solutions, but the Bullet M5 down in the building is working quite well and that's where it will remain.

Bob M.
In a case like this you can get an amplifier to overcome the coax losses. http://www.l-com.com/wireless-booster-5 ... rs?cmp=LM2
Fred Francis, Owner Xenirad Broadcast Engineering http://www.xenirad.com

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by kcbooboo » Thu Jan 29, 2015 4:44 am

Such an amp would do nicely up at the antenna, but that requires power somewhere on the tower plus a tower crew. If the station had all of that, they'd have installed the Bullet-M5 up there by itself already.

I looked at those amps. The 500mW unit only has 10dB gain, which is probably barely enough to be noticeable. Also they're supposedly not for sale in the US except to certain groups of users. While I could buy and use one as a licensed amateur operator, a radio station probably could not.

Cute idea though.

Bob M.

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Re: Replacing Harris Aurora 5800 Lan/T1 radio

Post by Xenirad » Thu Jan 29, 2015 6:12 pm

You would have to use the 3 watt or higher to get the full benefit and the amplifier would stay on the ground. This way you can overcome some of the coax loss. Even at 3 watts or 34.771 dbm you still only get 7.771 dbm to the antenna but that is much better than -4 dbm using the radio alone inside the building. The only other solution I know of is the Mikrotic Metal that puts out 1.3 watts or 31.139 dbm. http://routerboard.com/RBMetal5SHPn at $99 each this is a cheaper solution but there is a learning curve to Mikrotik products.
Fred Francis, Owner Xenirad Broadcast Engineering http://www.xenirad.com

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