Am setting up a 30m mast with 3 2.4ghz 2450freq flat 120deg flat sector antennas running on Station WDS Mode to cover about 20 clients to be powered by Solar
Equipment i have
I have 18dbi flat panels with 7dbi & 18dbi Backbone, RB532 indoor Router, a 30m mast, 2pc 120w Solar, 2000w Inverter Charger, Charge Controller and several solar 125amp batteries.
Advice
What type of cable and length should i use to connect all my 3 CPEs on the BTS to the Indoor Router?
What lightening equipment should be used and at which endpoints?
Am planning to do max 360deg 10km p2p on a flat surface with few trees above 7m in height. Will 18dbi 65mw be enough power to cover such a distance?
CPE normally means Customer Premises Equipment and goes at the customer end, not the transmitter site.
You don’t mention what frequency you’re working at 2.4GHz, 5.8GHz or something else?
The following cable loss calculations assume 2.4GHz, losses at 5.8GHz are approximaltey 1.6 times that at 2.4GHz.
I think you need to put your RB532 in an external case, if your router is going to be housed indoors then you’re going to have in excess of 30m of coax, 30m of HDF200 gives a loss of 15dB, HDF400 gives a loss of 6dB, thus EIRP will be 21 and 30dBi respectively. This takes no account of connector losses. Ideally you want the Coax cable to be as short as possible to minimise losses.
There are two schools of thought regarding lightning protection. First is that everything should be protected and grounded, the second is that nothing should be protected. I’ve had wireless equipment on a 10m tower for the last three years, the tower itself is grounded and has a lighting spike, but none of our equipment is grounded and we have yet to lose any equipment to lightning. All our problems have been with PoE cables being eaten by rodents and causing equipment to fail due to blown power circuitry.
Firstly it depends where you are located as you need to observe local regulations on maximum EIRP. In Europe we’re allowed 20dBi at 2.4GHz and 33dBi at 5.8GHz, in the US you are allowed up to 36dBi where directional antennae are used. Secondly it depends on whether you use an indoor unit and long coax cables or use an outdoor unit to minimise cable losses. You need to use a Link Loss calculator to determine the maximum distance for any given scenario. There are plenty of free calculators on the Internet. Don’t be tempted to try and install in marginal conditions, you’ll regret the unreliability later during periods of poor weather.
My final comment is regarding the Solar power. We have a Solar installation of 8 x 90W panels and 8 x 270Ah batteries. In strong direct sunlight we get around 40A @ 12V = 480W, but most of the time we get less than 100W. On good days we generate 3Kw total, but many days we generate less than 200W total. Our power consumption is just under 85W, i.e. 2.040Kw per day. Unless you are located in an area of reliable strong sunlight, I think you’re going to find your Solar/Battery capacity too small. For around 6 months of the year (October through March) we have to rely on a weekly boost charge from a petrol generator. We also have a 400W wind generator, but most of the time the wind is either too weak or too strong, it’s rarely just right!
You should use LMR 600 - nothing less for a 30m run. If the antennas dont need to be that high, you will gain signal by having a shorter cable.
Don’t run an inverter. Run everything off DC power. Have lightning arrestors at the bottom of each cable and ground them well. I’ve got two solar powered sites, and it’s all about efficiency and low power draw. It’s able to be calculated and be very reliable and long lasting. I just wish solar panels weren’t so costly.
Thanx cmacneill & Jp. Ill elaborate further on the issue
My first setup will use 2.5Ghz Band on 2412 Frequency (although i highly doubt if the frequency makes alot of difference). On the transmitter side i want to use 120deg sector panels 18dbi. I agree with cmacneill on using outdoor rb532; the loss off power using indoor is amazing!I’ll use 18dbi 120deg panels on the transmitter side using 2.4ghz band. Ill also check on the link loss calculator. JP, the LMR 600 cable, using indoor routerboard what’s the loss like? Mind you the cable might be more than 30m in length!I might also install the routeros on a cpu with 400mW cards instead of using routerboard, is this a better idea?
On lightening protection, i have a separate 17m mast housing an 18dbi Omni Antenna mounted 0.2m below the tip of the mast but i keep changing the cat6 cable every time its’ hit by lightening yet the mast is properly earthed to the ground and has an arrestor. Someone advised on using FTP cable. Can this work better?
On EIRP, the regulations are not that strict, i can still put up a strong powerful 35dbi link comfortably without any worries with the regulators. Infact on this 30m mast ill try a 70km p2p link on 5.8Ghz. I’ve never used NSTREME b4.
On power, i’ll have to solar. We have ample sunlight in desert areas of Northern Kenya temperatures of up to 50C so with 2 120w Panels, 6 125amp batteries, charger inverter, 3kva Generator (backup power charger to the batteries) & charge controller it will work. We don’t have the luxury for AC power here. I wish solar was cheap but the running costs for a full time generator here is 5times the solar. It will be better and cheaper to use solar and its stress free. The power load on all equipment we plan to use is less than 200w and with ample solar light, i think we can generate alot.
Sounds like your Solar may be OK. Power was our biggest problem, most days we have cloud cover, probably over 300 days a year! Don’t forget if you use a PC rather than RB it will use a lot more power.
6 x 125Ah = 750Ah, even with new batteries you will only get 50% of the rated capacity in practice = 375Ah, i.e. you can’t charge beyond 90% capacity and you can’t discharge beyond 40% capacity. Say you use 200W, then your total reserve is less than 24 hours without any top up. Personally I would prefer to see this nearer 7 days reserve, but then we can go a month without seeing the sun here!
LMR600 and other techologies such as wave guides are an option, but cost significantly more than LMR400 cable. We were quoted losses of 0.1dB/m @ 2.4GHz for LMR600, but it was 5 times the price of LMR400.
Watch out for 400mW cards, I’ve had a batch of Senao 8602 cards that just don’t work, they keep crashing the system and there are many other posts mentioning similar problems with high power cards from other suppliers. I’m currently using Wistron CM9 100mW cards, but my furthest customer is currently only around 3.5Km from the transmitter. My main problem is the 20dB EIRP @ 2.4GHz in the UK, that really kills long distance. For more than 4Km our only option is the 5.8GHz band.
If you are in a very dry area it may be difficult to make your earth protection low enough resistance to be of any use. Your earth spike really needs to penetrate the water table to get low enough resistance. In arid areas this could be 50-100ft down.
I’ll do a serious link loss calculation on various types of cables i.e LMR400, 600 & 900 and compare the costs vs returns since am starting small with less than 20 clients each on 256/128k link then upgrade to 5.8Ghz for long distance p2p. What is challenging at the moment is to get it right on power losses on cables and lightening arrestors which by now its getting clear thanx to you guys.
Most of my clients are less than 4km away therefore 2.4Ghz will work fine for me. For every client that i install a CPE, i want 2 configure it to a WDS system that can also do a hotspot using a 7dbi 2.4Ghz Omni which will doa a 200m hotspot cell. I aim at creating various metro hotspot cells for every CPE i install on the client side. Also i want to take advantage of clients further from my BTS but nearer a clients CPE on WDS mode so that it can get internet in grid manner. Is this possible or am i too ambitious? On my transmitter is my sector panels are on STATION WDS MODE can the above scenario work?
On power, i think more Amps on batteries plus additional batteries in a series connection will do the trick. 2 120watt panels, 6 12v 200amp batteries (high wattage)
Regarding power you say you may add batteries in series, this will change the voltage, not Ah capacity.
What make is your charge controller? I use an Outback MX60. Most Solar Charge Controllers allow you to have a different voltage on your Solar Array to Battery Bank. For best efficiency you should ensure that the voltage delivered by the Solar Array will always be more than the maximum charge voltage of the batteries. If you put your batteries in parallel you will have a nominal 12V bank, which has a maximum charge voltage of between 14.2 and 14.8V, the hotter the ambiant temperature the lower the maximum voltage. If you put your Solar Panels in series and allow the Charge Controller to step down the voltage to 12-15V you’ll be OK, but if you put the Solar Panels in parallel you may not get sufficient voltage to fullly charge the batteries.
The voltage of your battery bank is controlled to a large extent by your choice of Charger/Inverter as these are usually fixed voltage output.
I started off with 4 x 220Ah batteries in parallel and a 12V Charger/Inverter, so I’m stuck with 12V unless I replace it. It would be more efficient to have a 48V battery bank with pairs of batteies in parallel and then each pair coupled in series. Currently my backbone equipment (Alvarion BreezeAccess VL) is either mains power or 48V, but they are launching a 12V power unit shortly, so I’ll then take my power direct from the batteries rather than from the Inverter. However, if I installMT routers at this site ideally I’d want a 48V supply for PoE.
We’re using an Outback VFX2612 Charger/Inverter which is really excellant, however when using the petrol generator I usually put 10 litres of fuel in and leave it to run until the fuel is used. However, as the generator dies the power output fluctuates and causes the Charger/Inverter to put spikes on the 240V output, so I had to put in a small UPS to smooth it out, once I can use the 12V power units the problem will be solved.
At another relay location we have mains power, but I decided to put in a battery backup, due to the experience with the main site I put in a seperate Charger and Inverter, that way there can never be spikes put on the mains supply when the Charger cuts in and out.
I havent purchased a charger/inverter yet but sure ur advice is overwhelming detailed and precise. Thankyou very much for the info. Now let me get my hands dirty. I know ill get other tricky pratical scenerios which i’ll post here…cheers cmacneill
If you will, please tell us how many watts of solar panels you wound up using and what was the load, i.e., just gross numbers for economic feasibility?
I have a 100w and a 75w panel, 600ah of 12v (4 6v 300ah batteries, parallel and series), and a 15w load. 10 miles out in the ocean.
Another spot, I have the same panels, 300ah of battery, and a 10w load. 1 mile out in the ocean.
Morningstar charge controller, wet batteries, lots of grease to prevent corrosion. My radios use 5vdc, so I have a DC-DC converter.
It is overbuilt a little, but it is hard to get to (it’s hard to schedule a boat to a private island) The first location, they take down the wharf each winter so it is not destroyed by ocean storms - I have to row from the boat to the shore like an explorer. Second location is only accessible at high tide.
I’m sure Maine gets a lot less sun than Texas or Africa - there is stuff online to show how different areas of the world compare for average sunlight. We can get dark dank fog for 2 weeks straight, followed by rainy weather. reeks havoc on alcoholics and women going through post-partum depression.
below is the 2nd location before I added a second panel.