Digital Ready LNB?
Jeff Ireland
I have here what may be a silly question or two.....
I have worked in the satellite industry full time for quite a few years. Not
to date myself, but DEFINITELY pre 4dtv, as well as pre DSS and pre
P*,even. So please, no flames about "those damn self taught DSS
Installers!".
Lately, I see distributors offering (and mention of in usenet) "digital
ready LNBs". A large portion of my job has been providing maintenance /
repair to dish farms all across my state that utilize the C Band digital
platform. These farms are used primarily for the reception of simulcasting
of national thoroughbred and harness racing. Using primarily Scientific
Atlanta and GI (Primestar type C band receivers) technologies. I have always
just simply used higher quality residential dishes (Winegard Quadstar 10',
Uni Deluxe 10' & 12') with dual C feeds and the lowest K LNBs commonly
available-- many still operating in the field just fine that are 25K and
even 30K. Of course, these dishes aren't aligned with a homeowner grade toy
either. Set up with Spectrum Analyzer for optimum arc, focal dis, f to d,
and skew (Dual C - no polarizer servo remember).
So, after that spiel, what is the difference between a Norsat 15K or 17K and
a "Digital Ready LNB"?
I know I should know this (?), after I win the Lottery or earn my first
million, I'll pay someone to do my dirty work, and I'll hang in the office,
do "product research", read trade magazines and play on usenet all day! :-)
Thanks in advance for any relevant input
Jeff
K Tronics
neria-sandra
Apologies to you and group for not really answering...I'd like more info,
too!
I thought the difference had something to do with much tighter drift specs
in the digital, ergo much narrower bandwidth reception...
Someone who KNOWS--please inform!
Thanks!!!
Francesco
Jeff Ireland wrote in message ...
>Lately, I see distributors offering (and mention of in usenet) "digital
>ready LNBs".
GeorgeS
On Wed, 22 Apr 1998 11:52:57 GMT, "Jeff Ireland" <ktro...@mainewest.com>
wrote:
>I have here what may be a silly question or two.....
>So, after that spiel, what is the difference between a Norsat 15K or 17K and
>a "Digital Ready LNB"?
The digital ready are low phase noise LNBs, ie, the frequency of the local
oscillator is more stable than the regular LNB. The electrical noise rating is
a separate issue, and is measured as it is for the standard LNB. Until
recently, phase stable LNB s tended to have higer noise ratings.
From Mike Kohl
~~~~~~~~~~~~ Reference M Kohl on hardware ~~~~~~~~~~~~~~~~~~~~~
HARDWARE: LNBs (Low Noise Block Converter = L.N.B.)
_____________________________________________________________________
California Amplifier
Standard Consumer "Mini-Mag" C-Band LNB:
MINI MAG LNB Part No. 140011 [with LED is P/N 140078]
Presently available in 25 and 20 degree K grades.
INPUT FREQUENCY 3.7 to 4.2 GHz OUTPUT FREQUENCY 950 TO 1450 MHZ
TYPICAL GAIN IS 65 dB. CONNECTOR TYPE = F FEMALE
TYPICAL INPUT V.S.W.R. IS 3.0 to 1 DC VOLTAGE = +15 TO +28 VDC
TYPICAL OUTPUT V.S.W.R. IS 2.0 to 1 WARRANTY: 2 YEARS
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Premium Mini-Mag PLUS Low Phase Noise C-Band LNB:
MINI-MAG PLUS LNB Part No. 140103
Digi-Ready Low Phase Noise Technology
Presently available in 25 and 20 degree K grades.
Suitable for digitally-compressed video signals, and many
consumer SCPC applications.
Same specifications as Mini Mag LNB above, plus the following:
**LED Power Indicator is standard.
**Warranty is 3 Years.
Background information: New digital compression systems utilize
phase variations as a key part of the digital modulation scheme.
The ability to detect these subtle variations is hindered when the
phase of the downconverter's local oscillator is moving or jitter-
ing, resulting in excessive "phase noise". CAL AMP Digi-Ready
Low Phase Noise technology helps limit this condition to ensure
optimal performance of the digital system.
PHASE NOISE RATINGS: -70 dBc/Hz @ 1 KHz
-95 dBc/Hz @ 10 KHz
-115 dBc/Hz @ 100 KHz
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Digi-Ready PHASE LOCKED LOOP (PLL) Design
DIGI-READY C-BAND LNB Part No. 31846
This is a special order item, and meant for the commercial market.
Stability of the local oscillator is nearly 170 times that of the
conventional Mini-Mag residential LNB, and is achieved by the use
of CAL AMP's high stability Digi-Ready Phase Locked Loop Local
Oscillator, which helps limit the drift associated with typical
DRO "free running" oscillators. By limiting drift, narrow band
signals including SCPC and other digital formats which require
high stability over temperature are more easily "tracked".
This LNB is expensive, but necessary in commercial SCPC and many
digital applications. Typical stability of residential LNBs is
within 2 MHz. The Digi-Ready PLL unit above stays within 12 KHz.
**Warranty is 2 Years.
PHASE NOISE RATINGS: -63 dBc/Hz @ 100 Hz
-73 dBc/Hz @ 1 KHz
-89 dBc/Hz @ 10 KHz
-90 dBc/Hz @ 100 KHz
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Ted Mahler
Jeff Ireland <ktro...@mainewest.com> wrote:
> even 30K. Of course, these dishes aren't aligned with a homeowner grade toy
> either. Set up with Spectrum Analyzer for optimum arc, focal dis, f to d,
> and skew (Dual C - no polarizer servo remember).
So,,, If your ever in North Texas drop bye and say hello,, and
uhhhhh,,, bring your Spectrum Analyzer and other cool tools.
My BUD needs a little tweaking. C-band is great but that
dang KU is a tad off.
--
+----------__(')__-------------------------------+
l (')-//__l|l__\\ l
l \O_\/lol\/_O__ Ted Mahler (NAR 18184) l
l /O`. [ ] ;O_L\ (TRIP 1915) l
l _\__\_[ ]_/__/_/ (N5ZYO) l
l /'l l H l l'\ t...@sh-gpl.ti.com l
l /_\l___l_H_l___l/_\ l
l / '-H-` \ l
+-~~~--------~'~--------~~~----------------------+
John O'Donnell
Jeff
I can tell you from experience this week that you can have a lnb work perfectly
fine on an analog channel and not work on a digital. I had one go bad just
after 3 months of operation. The fix was put back my old 1.2. Will return the
.6 and get another later this week. There might just be something to what they
say about the new lnb's.
John
Jeff Ireland wrote:
> I have here what may be a silly question or two.....
> I have worked in the satellite industry full time for quite a few years. Not
> to date myself, but DEFINITELY pre 4dtv, as well as pre DSS and pre
> P*,even. So please, no flames about "those damn self taught DSS
> Installers!".
> Lately, I see distributors offering (and mention of in usenet) "digital
> ready LNBs". A large portion of my job has been providing maintenance /
> repair to dish farms all across my state that utilize the C Band digital
> platform. These farms are used primarily for the reception of simulcasting
> of national thoroughbred and harness racing. Using primarily Scientific
> Atlanta and GI (Primestar type C band receivers) technologies. I have always
> just simply used higher quality residential dishes (Winegard Quadstar 10',
> Uni Deluxe 10' & 12') with dual C feeds and the lowest K LNBs commonly
> available-- many still operating in the field just fine that are 25K and
> even 30K. Of course, these dishes aren't aligned with a homeowner grade toy
> either. Set up with Spectrum Analyzer for optimum arc, focal dis, f to d,
> and skew (Dual C - no polarizer servo remember).
> So, after that spiel, what is the difference between a Norsat 15K or 17K and
> a "Digital Ready LNB"?
GeorgeS
On Wed, 22 Apr 1998 13:59:18 GMT, pipn...@shore.net (GeorgeS) wrote:
>On Wed, 22 Apr 1998 11:52:57 GMT, "Jeff Ireland" <ktro...@mainewest.com>
>wrote:
>
>>I have here what may be a silly question or two.....
>
>>So, after that spiel, what is the difference between a Norsat 15K or 17K and
>>a "Digital Ready LNB"?
For a detaild reference on phase noise
Mini circuiuits RF/IF designers handbook
Page 15-6 VCO Phase noise
Roughly speaking, the phase noise is a measure of the bandwidth of the
VCO/Oscillator. VCOs with narrow bandwidth have low phase noise, VCO's with
wide bandwidth have large phase noise.
Now this phenomena is closely related to frequncy drift. If the oscillator
frequency drifts in time/temperature, than any measurement made over a
sufficiently long interval will show a wider spectral peak. Thus phase stable
LNBs are inherently frequency stable LNBs, hence their use in commercial SCPC
work.
Now in the dgital satellite signal domain, there are two transmission modes
SCPC amd MCPC (see Rod Hewitts site for a good description of the modes) . For
good reception of the digital SCPC mode, you need to lock onto the carrier
frequency, hence the utility of phase stable LNB.
The big contributor to frequency/phase drift is variation with temperature. In
analog SCPC, these differences are accomodated by using a seek function and an
AFC.
No doubt some digfital receivers have similar functions built in. but... they
probably have the nominal frequency hard coded , and search in a narrow band
about the nominal frequency. Once they lock on, they then use the AFC. This is
different from analog surfing of the SCPC channels. Using an anlog SCPC
receiver all you do is surf to the next active channel. The problem with
digital is that it is not sufficient to identify the frequency, you also need
other parameters (on DVB receivers you need the symbol rate and FEC).
This effect may describe the reason why some times the digital channels drift
in an out.It all depends on whether or not the oscillator has drifted into the
proper setting.
corn...@fuse.net
> > So, after that spiel, what is the difference between a Norsat 15K or
17K and
> > a "Digital Ready LNB"?
Saying "Digital Ready" LNB is like saying "Digital Ready" speakers or
amplifiers in the audio world. The reason an LNB fails on digital or
demanding SCPC reception is a function of drift and accuracy of the center
freq. My experience with the Norsat 15 is that it is a very stable LNB and
works well. The PLL (Phase Locked Loop) "digital" LNB's are more stable
still, and their price reflects this real performance advantage.
I have noticed that some of the worst drift performance I have seen has
come from CalAmp, specifically their 25 degree model. This is true of
LNB's a year or more old, I don't know if it holds true on newer product.
CalAmp does make PLL digital LNB's.
If an LNB drifts too fast or too far you may well find that it works fine
on analog reception but is either intermittent or fails completely on
digital. In this regard analog reception is a more robust system. A
stable LNB will give better analog performance as well, however. IMHO the
difference in picture quality between a standard 25 degree and a PLL 25
degree was not subtle on ITC analog.
Hope this helps.
Peace
Joe
GeorgeS
On 29 Apr 1998 12:01:29 GMT, <corn...@fuse.net> wrote:
>> > So, after that spiel, what is the difference between a Norsat 15K or
>17K and
>> > a "Digital Ready LNB"?
For those who like details... minicircuits (www.minicircuits.com) describes
how to measure phase noise with an HP 3084A on p27 of their VCO designer
handbook.
Steve Carter
GeorgeS wrote:
>
> On Wed, 22 Apr 1998 13:59:18 GMT, pipn...@shore.net (GeorgeS) wrote:
>
> >On Wed, 22 Apr 1998 11:52:57 GMT, "Jeff Ireland" <ktro...@mainewest.com>
> >wrote:
> >
> >>I have here what may be a silly question or two.....
> >
> >>a "Digital Ready LNB"?
>
--
Thanks Steve Carter
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