If you read the datasheets, they say a "guaranteed optical link budget" of 10dB for the 20km, and 14dB for the 40km.
On Tue, Dec 3, 2024 at 7:50 AM Ken Hohhof <khoh...@kwom.com> wrote: > Maybe shoot a question to FS, they seem pretty responsive. > > > > *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *Adam Moffett > *Sent:* Monday, December 2, 2024 11:44 PM > *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> > *Subject:* Re: [AFMUG] Optics light budget > > > > That's definitely true, but that affects how the light budget is consumed > not how much I start with. They give me the same Tx power and Rx > sensitivity regardless of which frequency I pick. > > > ------------------------------ > > *From:* AF <af-boun...@af.afmug.com> on behalf of Jim Bouse [Brazos WiFi] > <j...@brazoswifi.com> > *Sent:* Monday, December 2, 2024 10:04 PM > *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> > *Subject:* Re: [AFMUG] Optics light budget > > > > Different frequency light has different loss per km. > > > > Jim > > > > > > > > Sent via the Samsung Galaxy S22+ 5G, an AT&T 5G smartphone > > > > > > > > -------- Original message -------- > > From: Adam Moffett <dmmoff...@gmail.com> > > Date: 12/2/24 9:02 PM (GMT-06:00) > > To: AnimalFarm Microwave Users Group <af@af.afmug.com> > > Subject: [AFMUG] Optics light budget > > > > Help me understand this: > > > > 20km transceiver (SFP+ CWDM) > > https://www.fs.com/products/38707.html?now_cid=65 > > Max Tx power +6dBm. Rx sensitivity -14.4dBm. So a power budget of 20.4dB > > > > 40km transceiver (SFP+ CWDM > > https://www.fs.com/products/15385.html?now_cid=65 > > Max Tx power +5dBm. Rx sensitivity -15dBm. So a power budget of 20dB. > > > > What am I missing? These seem roughly equivalent. What makes one of > them more appropriate for the 40km distance? > > I looked at Precision OT as well. Their 40km CWDM SFP+ has a power budget > of about 20dB, and they don't even make a 20km one. Could this be kind of > like CPUs where the 20km ones are just 40's that didn't test well? > > > > -Adam > > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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