Yep. You'll be heard all over the valley with this 1 watt transmitter. Too bad you won't be able to hear any replies from the client radios because they're only using a few milliwatts. That's called an "alligator" or an animal with a big mouth and very small ears. I prefer to call it an RF polluter, but that's not being very diplomatic. Loose the power amplifier.
Dunno. You left out all the manufacturers and their part numbers. Looks like you posted a quotation from some dealer. There are equipment dealers lurking on this list. I'll let them contact you. However, if you can't find anything cheaper, you can always just punch in the manufacturer and part number into Froogle and get the lowest price:
The amp is to contact the access point on the far end of the valley (2 miles away, which also has an amp and directional antenna to this area.).
That's the reason for the amp, to make the distance to the other access point. and to quite honestly, burn through the trees. The line of sight distance to the other access point is very close to the horizon (more trees).
Initial tests, show the connection can be made if both sides of the connection are running at 200 mw. But we get -89-90 signal. Not enough for a stable connection.
So, you're going to be legally limited to a 6dBi antenna on this link. Such antennas are not very directional. If you're also operating a wireless system for clients in the same band, you're going to create substantial inteference.
Howeve, you mention "directional" antenna. You're still limited to
6dBi gain whether omni or directional with 1 watt out. See FCC
15.247(?) for the confusing rules and regs. If you're going to use a higher gain antenna, you're going to go well over the FCC limit.
Looking through your list, I see a 14dBi panel antenna which I presume is the corresponding link antenna. That's well over the limit and totally illegal. Were you to setup such a contrivance in my backyard, I would instantly report you to the FCC enforcement bureau as a gross polluter of the airwaves.
So, lets see what can be done without the power amplifier (which is incidentally the most expensive item on your shopping list). Start at for link calculations: |
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I'll make a few guesses as to your hardware and setup. Please correct as required. TX power = +15dBm TX coax loss = 4dB (3ft LMR-240 plus a mess of connectors) TX ant gain = +14dBi Distance = 2 miles RX ant gain = +14dBi RX coax loss = 4dB (same at other end) RX sens = -84dBm (at 12Mbits/sec) Fade margin = unknown Plugging into:
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get a fade margin of 8 dB which will not work. Changing the antennas to 24dBi barbeque grill antennas, this becomes a fade margin of 29dB which is well above the recommended 20dB minimum and will work just fine.
Loose the amplifiers and get some bigger antenna.
Oh, you have trees? How thick, what type, how many? Such things can be calculated (or guessed). Your 1 watt amplifier will yield a gain of about 15dB over the un-amplified output of about 15dBm. A MUCH cheaper dish antenna will yield 24dBi. You also have the benifits of having a much narrower beamwidth so that you pollute the valley. Also, the rules for point to point are quite different. With a 24dBi dish, you can legally run 24dBm power output maximum (about 300mw).
Well, that's another problem. If you're that close to the ground, the Fresnel zone clearance will be a major problem:
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2 miles, you have to have 26ft of clearance around the alleged line of sight.
Initial test using what equipment?
I suggest you look into 900MHz equipment that is made for going through trees:
That's what happens when I try to talk on the phone while writing. It should say:
Your 1 watt amplifier will yield additional gain of about 15dB over the un-amplified output of about +15dBm. A much cheaper dish antenna will yield 24dB of additional gain. You also have the benifits of having a much narrower beamwidth so that you will not pollute the valley with your overly broad and over powered signal. Also, the rules for point to point are different than point to multipoint. With a 24dBi dish, you can legally run 24dBm power output maximum (about
Please imagine this entire thread without any talk or mention of the amplier. Now, if you hadn't jumped on the 'bash the amplifier' band wagon. Could you have mentioned cheaper alternatives than to what was already mentioned?
The 900 mhz solution has been previously considered, but rejected because the base systems run around $1,000.
I guess you mean criticizing your method of implementation rather than finding a cheaper vendor. Not exactly my idea of hijacking a thread.
I think I did that when I suggested you look into using large antennas as an alternative to overpriced power amplifiers. I also did a rather detailed analysis of your link budget and the legal implications. There are 1 watt amplifiers that are slightly cheaper than $300. The difference is mostly in packaging, PoE, and whether they have an ALC (automagic level control) to allow the use of any length of cable between your bridge radio and the amplifier. However, since it appears that you have no interest in implementing a legal solution, I have no interest in becoming your accomplice.
True. Waverider hardware can be easily found on eBay for about $350 new. That's not exactly cheap but about the same as your $300 power amplifier. It also has the added benefit of being legal and working fairly well through the trees. If you did your site survey during the winter, when the trees have little foliage, it will become far worse in the spring (now) as the leafs appear.
There are other vendors of 900MHz solutions, but they are even more expensive.
I do have interest in legal and working. My concern now, is the cost of external boxes looks to be approaching $400 per site (will need 2).
External enclosure $70 POE hardware (from shaperconcepts.com) looks like it'll run $200 per (injector, plus power supplies Parabolic Dish $60-ish, plus mounting brackets and pipe, and mounts $40
That still doesn't cover connectors, (N to RP TNC), nor does it cover outdoor rated ethernet cable.
FYI, another reason 900 MHZ isn't an option. The county sherif and emergency services use 900 MHZ for their radios. All of the other corporate ISP provides have chosen to forgo 900 MHZ, even though it would make life easier for them in this hill/tree ridden environment.
802.11 wireless is from 902-928MHz. Public safety and Nextel are currently interleaved from 806-821MHz and
851-866MHz, nowhere near 902 to 928. They are currently going through a very messy and expensive frequency reorganization called "spectrum refarming". See:
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a simple frequency list. Note that there are no other services in the 902 to 928MHz range other than hams. If you're worried about interference, the high power paging transmitters on 929 to 931 will probably cause the most difficulties. Methinks you might wanna check the exact local sherrif and EMS service frequencies.
We have a small 900MHz non-802.11 system running in the forest.
I don't have an easy answer. Until you mentioned the trees, this was a no-brainer. A pair of 24dBi dish antennas, a pair of WRT54G or WAP54G bridge radios, a pair of NEMA boxes, some connectors, some pigtails, some hardware. No PoE because the WRT54G can handle a very wide voltage input range (4VDC to 18VDC). My guess is: dish $70 WRT54G $70 NEMA4 $40 pigtail $10 hardware $10 ============ $200 each end.
However, the trees and non-line of sight put a different picture on the link. Without having any clues as to what you're shooting through, I don't have any way to estimate the signal loss. Rule of thumb is about 10dB per broadleaf tree, but that varies radically by season. My original calcs showed a 29dB fade margin. That means you can probably waste 10dB and still have a useable system. That's a wall of trees that are one tree thick.
You mention that you were able to get a signal through the forest. Some questions:
What hardware and antennas did you use?
How thick a forest? With leaves or bare trees?
You're looking at 14" x 12" x 17". That's rather large and will probably cost at least $50 new. Look for PVC or fiberglass electrical boxes.
You don't need PoE for WRT54G. I'm not 100% sure about the WAP54G but I suspect it's similar. See previous description.
The PacWireless 24dBi barbeque grill dish that I use comes with a pipe mount. If you really need the pipe, see:
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$13.
The radio should be mounted near the antenna. Figure on about $12 for the pigtail. If you wanna get fancy, two pigtails with a double N barrel connector through the enclosure.
The Linksys WAPPOE12 box is not a "real" PoE as in 802.3af They're just a dropping resistor or maybe a regulator. See thread at: |
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