Ok Andrea,
Op simply (ish) uses time to determine the s/n level , by virtue of
the power / time .. the time's in data terms are very long , but as
compared to existing systems is a improvement ..
For each X2 time, there is a 3 dB advantage , OP2 = -26 dB OP4 -29dB
OP8 -32dB etc
wspr minimum decode -32 / -34 dB .. so that's -8 or -6 db correction
factor.
Interestingly this puts the OP4H 8Khz mode past -50 dB decode level if
you comparer to the higher 'standard'
Remembering wspr may be peak reading and Op average , its also
possible Op will decode below the stated level's, due to the average s/n
measurement.
One of the main thing are , stations are getting good results with the
minimum of hardware, overall frequency stability requirements for OP32
is approx +/- 2 Hz over the 32 min period , widening as the time
reduces. ( I think its a linear ratio ..but will check, that makes OP4
(500Khz) +/- 16 Hz)
Q what Ae and power is used ?
Good luck , G..
--------------------------------------------------
From: "DP engineering" <[email protected]>
Sent: Thursday, April 26, 2012 2:39 PM
To: <[email protected]>
Subject: Re: LF: info about better digital mode in 2200m band
I know for sure that lentus and K1JT's modes are comparable.
They both use the "stadard" definition: signal power/noise power over
2500Hz band/signal
In my mind roughly : Opera2=WSPR, Opera8=WSPR-6db, Opera32=WSPR-12db
Do you think it's correct?
Opera2=WSPR states that Opera il less efficient (same period for less
information). But Opera don't require any kind of syncronization.
LENTUS = WSPR - 7db For me it's reasonable (same information, more time
to trasmit it, no pseudo-random sequence for syncronization, less "code
gain" but more "symbol" gain)
OK, making comparisons is not so easy... maybe also my conclusions are
discutable
I5ZPO / IW5BHY Andrea
----- Original Message -----
From: [email protected]
To: [email protected]
Data: Thu, 26 Apr 2012 13:49:32 +0100
Subject: Re: LF: info about better digital mode in 2200m band
Just one or two thing's to check
The S/N readings produced by Opera are referenced to the SIM - PATH
software , so s/n levels shown are calibrated to a different standard
The original system was calibrated to be similar to fldigi / wspr ,
but
after a series of tests by members of the yahoo digital group,
Jose
, felt these levels where not realistic and re calibrated , giving
a
lesser reading. Im not sure as what Patrick has referenced his modes
to, but if lentus system is similar to jt65 etc , then you will need
to add a conversion factor.
As a yard stick , OP2 @ -26dB S/N is similar to WSPR,
Also note the Op s/n levels are all indicated as Average , over
the time line , so if you only decode 50% of the transmission
(sufficient for decode) then the s/n level will show as -3dB
compared
to 100% decode
The Opera system has also a QSO mode using the same coding
system, but is set to 120 second TX period for 15 characters
and operates round the -20 dB s/n level
Set Op to 500 Khz for access to the qso mode if wanting to try, but
you do need -20 dB s/n for decode,
ROS-MF7&2 mode is available ,multi tone, 99Hz b/w at 2 baud , this
operates at the same S/N of WSPR , but needs AUDIO/SDR Tx
facility. however it is a live rtty mode with no 'time frame' or
'time
locking' MF-7 is 6 / 7 dB less, but has a chr rate similar to
psk31....
73 -G..
The OP system is still under development , so if users have any
requirements etc , pls write in<<<
--------------------------------------------------
From: "DP engineering" <[email protected]>
Sent: Thursday, April 26, 2012 1:10 PM
To: <[email protected]>
Subject: Re: LF: info about better digital mode in 2200m band
Hi Mauro,
At the present, I think Opera is the most widely used.
WSPR reaches -27db, not enough for covering long distances on LF. So,
it's
rarely used.
Opera and lentus perform better:
Lentus reaches -34db for 5 minutes trasmission, Opera8 and Opera32
(8/32
minutes trasmission) reach -32db and -38db respectively.
In my opinion, technically speaking, Lentus is the best (it is also very
good for making QSO). Lentus requires a very good syncronization among
station. In addition, if you use a SDR, you may have some problems due
to
the latency of the SDR.
Instead, Opera is very simple and very close to the "regular" QRSS.
So, my conclusions are:
For medium distance beacons : Opera8 or Lentus
Foe long distance beacons : Opera32
For QSO : Lentus
best 73's'
I5ZPO Gino (operated by IW5BHY Andrea)
----- Original Message -----
From: [email protected]
To: [email protected]
Data: Thu, 26 Apr 2012 12:27:27 +0200
Subject: LF: info about better digital mode in 2200m band
Hi,
what is the better digital mode for starting listening 137 KHz
band as "reverse beacon" (no TX)??
("better" = greater number of active stations in Europe)
WSPR ?? LENTUS ?? OPERA ??
what frequency is utilized for those modes ???
thanks in advance to all ..
73 de Mauro IK1WVQ
P.S.: my RX station is : PA0RDT 8 meters over the roof, RACALL 1792
.. not great station at all ..
in QRSS mode the only station what I can receive is the "broadcast
(HI!)" beacon of Stefan DK7FC .. NO OTHER ...
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