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PA2AGA > HDDIG 18.06.00 04:41l 191 Lines 7392 Bytes #-9440 (0) @ EU
BID : HD_2000_167C
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Subj: HamDigitalDigest 2000/167C
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Sent: 000617/2335Z @:PI8HGL.#ZH1.NLD.EU #:52335 [Den Haag] FBB $:HD_2000_167C
From: PA2AGA@PI8HGL.#ZH1.NLD.EU
To : HDDIG@EU
Date: Sun, 18 Jun 00 00:19:22 MET
Message-Id: <hd_2000_167C>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
"Efficiency" being the approximate ratio of real data bytes to total bytes
sent. For example, "60% efficiency" corrects the most errors but has the
lowest net effective data throughput rate.
To compare apples with apples, you MUST compare the maximum theoretical data
throughput rates of CLOVER II with PACTOR II with PACTOR II's data
compression TURNED OFF. You must also specify the Reed Solomon coder
efficiency, the modulation scheme and the block size being used by CLOVER
II.
HAL likes to say that the MAXIMUM theoretical effective data rate of CLOVER
II using the 16P4A modulation scheme, a block size of 255 bits and FAST bias
is approximately 750 bits per second. This number is VERY misleading. You
must look for the following disclaimer in HAL's description of the CLOVER II
protocol:
"Note that while the "Effective Data Rate" numbers listed in Table 2 go as
high as 750 BPS (bits-per-second), inclusion of other desired features in
CLOVER-II add overhead and thus reduce the net throughput or overall
efficiency of a CLOVER transmission"
In REALITY, CLOVER II's maximum theoretical data throughput rate is
approximately 557 bits per second using the 16P4A modulation scheme, a block
size of 255 bits and fast bias (i.e. VERY little error correction using the
Reed Solomon FEC). (See page 15 of HAL's description of the CLOVER II
protocol. In the table, you will see that HAL states that the MAXIMUM
effective data throughput rate for 16P4A is 69.6 bytes per second (or 557
bits per second)).
This is a THEORETICAL number. In my experience, you really need VERY STRONG
and STABLE signals to reach this theoretical maximum. It is rare that you
will reach this theoretical maximum with typical signals on HF. In my
experience, you are more likely to reach a maximum effective data throughput
rate of 372 bits per second using the 8P2A modulation scheme, a block size
of 255 bits and fast bias (i.e. VERY little error correction using the Reed
Solomon FEC).
In contrast, the MAXIMUM theoretical data throughput rate in PACTOR II is
approximately 600 bits per second WITH ITS DATA COMPRESSION TURNED OFF! (I
think the actual number is 589 bits per second).
EVEN WITH PACTOR II's DATA COMPRESSION TURNED OFF, PACTOR II HAS THE HIGHER
THEORETICAL MAXIMUM DATA THROUGHPUT RATE THAN CLOVER II (i.e Compare 589
bits per second using PACTOR II with 557 bits per second with CLOVER II).
Admittedly, the difference between the MAXIMUM theoretical data throughput
rates is NOT that great.
But in my view, there is EVEN a BIGGER distinction between CLOVER II and
PACTOR II. The THEORETICAL maximum data throughput in PACTOR II is MUCH
more likely reached on the HF bands! It is NOT simply a theoretical number.
With PACTOR II, you do NOT need signals NEARLY as strong and stable as with
CLOVER II to reach PACTOR II's theoretical maximum UNCOMPRESSED data
throughput rate of approximately 600 bits per second. In other words,
PACTOR II reaches its maximum data throughput rate under MUCH POORER
CONDITIONS with MUCH WEAKER signals than CLOVER II.
Furthermore, with Pseudo Markow data Compression (PMC) and run line
encoding, the MAXIMUM data throughput rate using PACTOR II is approximately
1120 bits per second. But like all data compression algorithms, the actual
maximum data throughput REALLY depends on the type of data being sent.
If you send plain text ASCII files, then you may reach the theoretical
maximum data throughput of 1120 bits per second using PACTOR II. If you are
sending BINARY files, the maximum data throughput will be a lot lower.
I have used both CLOVER II and PACTOR II. In my view, there is NO
comparison. EVEN with its data compression TURNED OFF, PACTOR II is VASTLY
superior!
PACTOR II is amazing. It does NOT need strong and stable signals for truly
amazing data throughput. PACTOR II also reaches its maximum data throughput
rate under MUCH POORER CONDITIONS with MUCH WEAKER signals than CLOVER II.
In contrast, I found that CLOVER II rarely uses its 16P4A modulation scheme
even with fairly strong and stable signals. In my view, under typical HF
conditions, you are more likely to reach a MAXIMUM effective data throughput
rate of 372 bits per second using CLOVER II (with its 8P2A modulation
scheme, a block size of 255 bits and fast bias).
For charts comparing PACTOR II with CLOVER II, go to the SCS web site at
www.scs-ptc.com. In my view, these charts are pretty accurate. They
reflect my experience. SCS tries to compare apples with apples by showing
the different effective data throughput rates for PACTOR II, CLOVER II,
PACTOR 1 etc with PACTOR II's data compression turned off.
For details on the CLOVER II protocol, go to the HAL web site at
http://www.halcomm.com/. Click on technical documents and select the E2006
article number.
In my view, it is clear what is the fastest HF TOR mode used by HAMs today.
It is PACTOR II.
73's
Rob
F.Y.I. -- the HAL CLOVER controllers also implement a P-MODE protocol which
is supposed to be compatible with PACTOR 1. The HAL controllers do NOT
implement the PACTOR II protocol even though some of their product flyers
refer to PACTOR II in an obscure way (at least in my view). I do not think
that the HAL P-MODE is exactly the same as the PACTOR 1 protocol. It sounds
a little different to me.
Personally, I experienced problems when using the HAL DXP-38 on its so
called "P-Mode". I can't recommend the HAL DXP-38 if you plan to make a lot
of PACTOR 1 QSO's. (PACTOR 1 is a very popular mode). On the other modes,
the HAL DXP-38 worked well.
"Tor Tveitane" <tor@bushsoft.com> wrote in message
news:t__15.1264$eI.25791@news1.online.no...
> Hank Oredson <horedson@att.net> wrote in message
> news:jBU15.1888$Xx5.130931@bgtnsc06-news.ops.worldnet.att.net...
> >
> > "Tor Tveitane" <tor@bushsoft.com> wrote in message
> > news:O5R15.999$eI.19947@news1.online.no...
> > > Hi,
> > >
> > > What is currently the fastest and hottest HF mode in use??
> > >
> > > I have been using a Kantronics with GTOR several years ago, but sure
> there
> > > must be something faster today...?
> >
> > Pretty much equal between CLOVER and PACTOR-II.
> >
> > They are very close, with PACTOR-II having a weak signal advantage,
> > and CLOVER having a bulk transport advantage.
>
> Hi,
>
> Thanks for the feedback.
>
> Which baudrates can I expect...?
>
> And... do anyone of you know how these modes throughput compares to
CODAN's
> radio modem systems. (They are Hayes AT compatible).
>
> regards
>
> Tor
>
> >
> > > Thanks in advance if you have comments, URLs and pros/cons...
> >
> > www.halcomm.com
> > www.scs-ptc.com
> >
> > > regards
> > >
> > > Tor
> >
> >
> > --
> >
> > ... Hank
> >
> > http://horedson.home.att.net
> >
> >
> >
>
>
------------------------------
Date: Fri, 16 Jun 2000 01:59:35 GMT
From: "Hank Oredson" <horedson@att.net>
Subject: Hottest and fastest HF mode
"Rob" <Pse@NoEmail.Com> wrote in message
news:ktd25.10532$qS3.27654@tor-nn1.netcom.ca...
> Well I hate to disagree with HANK. But even for bulk data transport, based
> on my experience, it is my opinion that PACTOR II is VASTLY superior to
To be continued in digest: hd_2000_167D
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