The spec sheet does say guaranteed minimum link budget of 10dB. Even at minimum tx power of +1 to Rx sensitivity of -14.4 that's still over 15dB. The 20km unit supposedly has lower reflectance too. There's some math here beyond my pay grade, or yeah maybe the specs are just wrong.
I guess I'll ask the source. -Adam ________________________________ From: AF <af-boun...@af.afmug.com> on behalf of ch...@go-mtc.com <ch...@go-mtc.com> Sent: Tuesday, December 3, 2024 11:33 AM To: AnimalFarm Microwave Users Group <af@af.afmug.com> Subject: Re: [AFMUG] Optics light budget Sounds like error in specs. You know there is a difference. From: castarritt Sent: Tuesday, December 3, 2024 8:45 AM To: AnimalFarm Microwave Users Group Subject: Re: [AFMUG] Optics light budget 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 ________________________________ -- AF mailing list AF@af.afmug.com http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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