Subject: RE: Looking for a Satellite Link Emulator

From: "Senecal, Mark" <[email-masked]>
Date: Tue, 28 Sep 1999 10:18:34 -0400

Cheryl,

	I do not believe there is such a device for that high of a Bitrate.
The most common Maximum Bitrate used over satellite is around 40-50 Mb/s.
This is due to the satellite is most cases. For example a Ku-Band
transponder is 54MHz and is typically split into two transponders of 27MHz
which would limit you to around 26-30 Mb/s. Now C-Band is around 36MHz which
will allow for a higher Msymbols/s rate of around 31Ms/s with an FEC of 7/8
you could achieve above 40Mb/s. As you can see this is significantly lower
than an OC-3 Bitrate. I know some manufactures have been playing around with
using an entire 54MHz Ku-Band Transponder but I have not heard of any
positive results. 

	Now that is all for QPSK modulation if you were to use 8PSK you
could use an entire C-Band Transponder to get up to 70Mb/s, BUT you would
have to increase the size and power of your antenna's in order to maintain
the same quality of signal as the QPSK. (Expensive undertaking). This is
still less than half of an OC-3.

	The only solution that I can see is to split up your uplink over
multiple transponders then re-multiplex it at your downlink. If you have any
new information about this I would be very interested in hearing it.

Mark Senecal
Scientific Atlanta Canada Inc.
[email-masked]
tel (416) 321-7794
fax (416) 299-7145

-----Original Message-----
From: Cheryl DeMatteis [mailto:[email-masked]]
Sent: Monday, September 27, 1999 12:56 PM
To: [email-masked]
Subject: Looking for a Satellite Link Emulator

I need to use a Satellite Link Emulator that can sustaine OC3 data
rates for a development lab.  If anyone has any experience with such a
product could you share your experiences with me.

Thanks,
Cheryl

-- 
Cheryl K. DeMatteis                      The Aerospace Corporation, M1/102
[email-masked]                         Computer Science and Technology
(310)336-1189                            2350 E. El Segundo Blvd. 
(310)336-4402 (fax)                      El Segundo, CA 90245-4691

---

From: "David R. Beering" <[email-masked]>
Date: Tue, 28 Sep 1999 11:59:33 -0500

RE: Looking for a Satellite Link Emulator
Folks:

These devices do exist.

Check out www.adtech-inc.com

Adtech is based in Honolulu, Hawaii. They manufacture broadband test and
simulation equipment, including satellite link emulators operating up to
OC-3c rates. The high-end emulator is called the SX/14. Its little brother,
the SX/13, supports rates up to 51 Mbps. These units do channel impairment,
as well as delay simulation well beyond GEO.

We have used the SX/14 extensively to model tests that were performed on
NASA's Advanced Communications Technology Satellite at 155 Mbps and 622
Mbps. Hope this helps.

Regards,

    Dave Beering
    Infinite Global Infratructures, LLC
    [email-masked]
    630-665-1396 (Office)
    630-235-7965 (PCS)

  -----Original Message-----
  From: [email-masked] [mailto:[email-masked]]On
Behalf Of Senecal, Mark
  Sent: Tuesday, September 28, 1999 9:19 AM
  To: [email-masked]
  Subject: RE: Looking for a Satellite Link Emulator

  Cheryl,

          I do not believe there is such a device for that high of a
Bitrate. The most common Maximum Bitrate used over satellite is around 40-50
Mb/s. This is due to the satellite is most cases. For example a Ku-Band
transponder is 54MHz and is typically split into two transponders of 27MHz
which would limit you to around 26-30 Mb/s. Now C-Band is around 36MHz which
will allow for a higher Msymbols/s rate of around 31Ms/s with an FEC of 7/8
you could achieve above 40Mb/s. As you can see this is significantly lower
than an OC-3 Bitrate. I know some manufactures have been playing around with
using an entire 54MHz Ku-Band Transponder but I have not heard of any
positive results.

  Mark Senecal

  -----Original Message-----
  From: Cheryl DeMatteis [mailto:[email-masked]]
  Sent: Monday, September 27, 1999 12:56 PM
  To: [email-masked]
  Subject: Looking for a Satellite Link Emulator

  Thanks,
  Cheryl

---

From: Anthony Stone <[email-masked]>
Date: Tue, 28 Sep 1999 21:53:57 +0200

Mark,

The numbers you quote are from a North American perspective. Here in 
Europe Eutelsat sells 72 MHz wide Ku-Band transponders on their 
W-series satellites. We've been operational on one of these for 
nearly a year, transmitting IP to and from our international hubs 
using 8PSK modulation. It works well.

Regards,
Anthony Stone
Satellite Projects
EUnet International (now KPNQwest)

>Bitrate. The most common Maximum Bitrate used over satellite is 
>around 40-50 Mb/s. This is due to the satellite is most cases. For 
>example a Ku-Band transponder is 54MHz and is typically split into 
>two transponders of 27MHz which would limit you to around 26-30 
>Mb/s. Now C-Band is around 36MHz which will allow for a higher 
>Msymbols/s rate of around 31Ms/s with an FEC of 7/8 you could 
>achieve above 40Mb/s. As you can see this is significantly lower 
>than an OC-3 Bitrate. I know some manufactures have been playing 
>around with using an entire 54MHz Ku-Band Transponder but I have not 
>heard of any positive results.
>
>        Now that is all for QPSK modulation if you were to use 8PSK 
>you could use an entire C-Band Transponder to get up to 70Mb/s, BUT 
>you would have to increase the size and power of your antenna's in 
>order to maintain the same quality of signal as the QPSK. (Expensive 
>undertaking). This is still less than half of an OC-3.
>
>        The only solution that I can see is to split up your uplink 
>over multiple transponders then re-multiplex it at your downlink. If 
>you have any new information about this I would be very interested 
>in hearing it.
>
>Mark Senecal
>From: Cheryl DeMatteis 
>[<mailto:[email-masked]>mailto:[email-masked]]

---

From: "William Conaway" <[email-masked]>
Date: Tue, 28 Sep 1999 15:50:23 -0400

RE: Looking for a Satellite Link EmulatorMark
I have been observing this thread for several exchanges and notice that
everyone seems to be wrapped around the axle assuming that Cheryl is talking
of a commercial satellite.  Before jumping in with potentially wrong
conclusions, look at the domain name of the person asking the question and
then if necessary do a little research.  There are satellites up there that
have considerably wider bandwidths that get used on a regular basis.  They
don't all fall into the .com domain.

As far as a channel simulator, visit http://www.adtech-inc.com/index.htm for
an operational OC-3 simulator
  -----Original Message-----
  From: [email-masked] [mailto:[email-masked]]On
Behalf Of Senecal, Mark
  Sent: Tuesday, September 28, 1999 10:19 AM
  To: [email-masked]
  Subject: RE: Looking for a Satellite Link Emulator

  Cheryl,

  Mark Senecal

  -----Original Message-----
  From: Cheryl DeMatteis [mailto:[email-masked]]
  Sent: Monday, September 27, 1999 12:56 PM
  To: [email-masked]
  Subject: Looking for a Satellite Link Emulator

  Thanks,
  Cheryl