Satellite Internet forum | |
https://www.satsig.net/cgi-bin/yabb/YaBB.pl
VSAT technology and installation >> iDirect Forum: hubs and terminals >> Re: The saturation aspect on tdma transmission https://www.satsig.net/cgi-bin/yabb/YaBB.pl?num=1239095300 Message started by TDMAMike on Apr 7th, 2009 at 12:03pm |
Title: Re: The saturation aspect on tdma transmission Post by TDMAMike on Apr 7th, 2009 at 12:03pm
Please elaborate on your question.
You certainly need to determine your BUC/SSPA requirement to close specific data/symbol rates. TDMA or not, the BUC must be able to close the symbol rate of the upstream/return carrier it is operating in (without saturating/distorting). For example: A system operating in a 2048k upstream must be able to close the full 2048k return (and meet the UCP for the inroute group). That is why a good 1dB compression test is necessary. |
Title: Re: The saturation aspect on tdma transmission Post by Eric Johnston on Apr 7th, 2009 at 8:27pm sagigadasi wrote on Apr 7th, 2009 at 1:04pm:
If the hub has different inroute groups with different symbol rates but all using the same modulation and FEC then doing what is suggested will reduce the required BUC power by 3 times and probably enable it to be operated out of saturation, but at the penalty of reducing the customer bit rate to one third. Quote:
If you leave the power, bit rate and FEC alone and alter the modulation BPSK - QPSK - 8PSK - 16QAM the effect is as you describe, the bandwidth alters, the power spectral density alters and the power stays the same throughout. Quote:
Quote:
Yes, the section of transponder leased, e.g. 1 MHz, has a specific entire maximum uplink power or earth station eirp allowed into it. If, for example, this is equivalent to 4 watts from a 1.2m dish then you might use the 1 MHz for four TDMA carriers, one rated at 2 watts into 1.2m dish and using 500 kHz, and two others, each rated at 1 watt into 1.2m dish, each occupying 250 kHz. Say 360 and 180 and 180 kbit/s data. I hope this helps. It is bit complicated to explain briefly. Best regards, Eric. |
Powered by YaBB 2.5.2! YaBB Forum Software © 2000-. All Rights Reserved. |