| |
PA2AGA > HDDIG 01.09.00 22:58l 185 Lines 6263 Bytes #999 (0) @ EU
BID : HD_2000_236C
Read: GUEST
Subj: HamDigitalDigest 2000/236C
Path: DB0AAB<DB0ZKA<DB0ABH<DB0SRS<DB0CWS<DB0AIS<DB0ME<DB0OVN<PI8JOP<PI8ZAA<
PI8WFL<PI8HGL
Sent: 000901/2049Z @:PI8HGL.#ZH1.NLD.EU #:9178 [Den Haag] FBB $:HD_2000_236C
From: PA2AGA@PI8HGL.#ZH1.NLD.EU
To : HDDIG@EU
Date: Thu, 31 Aug 00 16:47:47 MET
Message-Id: <hd_2000_236C>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
range with Earth curvature is 81 miles.
Eq. 1 d = sqrt(17*h) Distance of the path in kilometres
Where h = 1000 metres
Then
d = 130 km or 81 miles.
Thus, 150 miles is out of the question unless you raise the antenna height.
Solving for h, we can re-arrange to:
sqrt(h) = [d / sqrt (17)]
Eq. 2 h = [(241 / 4.1231)]^2
h = 3417 metres - (1000 metres elev diff) or 7930 ft
You could split this between the two sites, and say have two 4000 ft antennas.
Most microwave links are 40 miles (64 kilometres). Plugging this into Equation
2,
we find that the antenna would have to be 791 feet high if both were at sea
level,
but since one station is 3280 feet higher than the other, you should be able
to
use roof-top antennas given no obstructions.
To do what you desire, I would say, you need about 4 hops (the two ends, and
two repeaters in-between. You would need about 10 Watts per radio into a
microwave dish. 10 Watts in an in-line amp at 2.4 GHz is about $2k to $3k per
node, or about $8k to $12k USD.
Using a Spread Spectrum radio like the Proxim 7921, you can expect about 7
miles per hop, or about 21 hops (the two ends, and 19 repeaters). Each
repeater
costs about $500 (radio, antenna, misc), or about $10k USD. Each repeater
has a 30 ms latency, or a path latency of 6.3 seconds (a packet leaving
your node would arrive about 6 seconds later at the end-node).
Looking at the above, I'd say that unless you are very wealthy, and have
money to blow (.com stock) you would be better off buying a sail boat and
a couple cases of beer. It would be infinitely more fun.
Yours Truly,
Jimmy
"Teamsters == Organized Crime"
"Sarel J. Botha" <sjbotha@email.com> wrote
>
> With one hop, do you mean 1 repeater? The topology between the points is a
> bit hilly. The other point is near the coast and so is at sea level. There
> is about a kilometer (0.65 miles) difference in height between the 2 points.
>
> Isn't there any way of making sure if it's possible to do what I want?
------------------------------
Date: Wed, 30 Aug 2000 10:28:36 +0300
From: Paul Keinanen <keinanen@sci.fi>
Subject: Distance?
On Mon, 28 Aug 2000 22:43:59 +0200, "Sarel J. Botha"
<sjbotha@email.com> wrote:
>Is there a frequency on which I can send data at a decent rate (64k/s) over
>about 150 miles? I'm looking for very low-budget equipment.
At that distance a VHF/UHF troposcatter link might be possible.
Troposcatter links have been used e.g. to provide telephone services
to North Sea oil rigs.
At 240 km distances the troposcatter path loss on VHF/UHF is less than
200 dB for about 99 % of the time. These are worldwide averages and
the loss can vary from region to region.
Maybe about -110 dBm of received signal is required to transfer 64
kbit/s. Antenna systems with multiple yagis at both sites may have a
gain of 20 dB on each site. The antennas must have a clear view of the
horizon (0 degree elevation), any local obstacles above 0 degree
elevation will increase the path loss by 10 dB for each degree.
With 100 W (+50 dBm) transmitter power, the received power would be
+50+20-200+20=-110 dBm or just sufficient for 64 kbit/s. The regional
phase loss variations can be large and there can be seasonal
variations also, so you may have to be prepared to use 1 kW
transmitter power or drop the speed to 9600 bit/s.
Ordinary FSK and PSK will suffer quite a lot distortion from
troposcatter propagation and this may require the use of some more
robust modulations, such as spread spectrum or COFDM.
If this is not an amateur radio application, then these sites needs to
be licensed, requiring frequency allocation and station inspections.
So neither is this a low budget alternative.
You might check for satellite based Internet operators if they provide
service in your region. Some require an ordinary phone line for
uplink, while at least some plan to have systems in which the user
also has a satellite uplink transmitter. However, this may require
special licensing arrangements in some countries.
Paul OH3LWR
------------------------------
Date: Tue, 29 Aug 2000 16:28:17 -0400
From: ZZZjim_cronin@juno.comZZZ
Subject: FS: PK-96 TNC
For sale: AEA PK-96 dual speed TNC.
Does 1200 and 9600 baud on the same radio.
$140 shipped to lower 48. Call Jim at 716-231-2417 (work) or
716-381-3102
(home before 9 EST) or send email to
ZZZjim_cronin@juno.comZZZ (remove leading and trailing ZZZ).
Thanks and 73,
Jim
N2VNO
------------------------------
Date: Tue, 29 Aug 2000 16:27:20 -0500
From: "J. Hoffa" <J.Hoffa@underground.net>
Subject: MUSCLES
Too often, we lose sight of life's simple pleasures.
Remember, when someone annoys you it takes 42 muscles
in your face to frown; BUT, it only takes 4 muscles to
extend your arm and bitch-slap the motherfucker upside
the head..
pass it on...
------------------------------
Date: Wed, 30 Aug 2000 03:55:47 GMT
From: Chuck <sulch@gte.net>
Subject: Service Manual Icom IC-211
Hello, I am in need of a factory service manual, or a copy thereof; I
have a 211 that is from 2.5KHz to as high as 19KHz higher than
displayed frequency both TX and RX. When first powered up it is right
on frequency then drifts the amount previously mentioned; however,
once warmed up the drift stops and the unit is stable from there on.
If anyone out there can help it would be most gratefully received,
please reply to sulch@gte.net
Thank you,
73s Chuck KG4ESR
------------------------------
Date: Tue, 29 Aug 2000 14:07:37 GMT
From: Brian Hemmis <K3USC@att.net>
Subject: WTB- Kantronics KPC-3
Wanted KPC-3. Mine died and I need a replacement for Packet Clucter DX
spotting. Let me know what you have and how much $$. Thanks in advance,
Brian K3USC-Erie, PA, 814-866-2585 or email
------------------------------
End of Ham-Digital Digest V2000 #236
******************************
You can send in your contribution to this digest by
sending an e-mail to: hd-group@pa2aga.ampr.org
or (via BBS-net) to: hdaga@pi8vnw.#zh2.nld.eu
Read previous mail | Read next mail
| |
