[Sis-csi] 2:30 Eastern it is

[Ivancic, William D. (GRC-RCN0)]

Once the frame of reference changes from and Earth/Space architecture to
rover/habitat/relay/large spacecraft/relay/earth  it becomes difficult
to determine what a forward and return link are - particularly if links
become less asymmetric.  
 
I find the terms transmit and receive useful in my mobile wireless
experiences as we usually have the modulator control the transmit clock
and feed the router serial card transmit clock.  The demodulator
controls the receive clock and feeds the router serial card receive
clock and associated data.  Thus, the router interfaces use DTE cables.
This allows for transmit and receive to be different data rates while
using one serial port on a COTS router.  This cabling is shown in figure
28 of the CLEO/VMOC report in Appendix D.
 
 
When emulating RF links without radios the routers both use DCE cables
and control the transmit clock while using the other ends transmit clock
as its receive clock.   This cabling is shown in figure 27 of the
CLEO/VMOC report in Appendix D.
 
http://roland.grc.nasa.gov/~ivancic/papers_presentations/2005/cleovmoc.p
df

I purposefully documented the cabling in this report as it can get quite
confusing.  Hopefully, this will save someone a lot of headaches when
building up testbeds.


Will


******************************

William D. Ivancic

Phone 216-433-3494

Fax 216-433-8705

Lab 216-433-2620

Mobile 440-503-4892

http://roland.grc.nasa.gov/~ivancic
<http://roland.grc.nasa.gov/~ivancic>  

 


________________________________

	From: sis-csi-bounces at mailman.ccsds.org
[mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Adrian J. Hooke
	Sent: Thursday, January 25, 2007 4:40 PM
	To: Cislunar Space Internetworking
	Subject: RE: [Sis-csi] 2:30 Eastern it is
	
	
	At 12:41 PM 1/25/2007, Scott, Keith L. wrote:
	

		"What is 'uplink'?"


	Aren't the correct terms "forward link" and "return link"?
	
	///adrian