Hi all, just wondering if anyone has deployed any 4600c ptp links beyond 13KM (8miles) and have some real world results? Guess just wondering who has the longest 4600c link out there lol, cheers!
Location is probably an important part of this question. With the eirp rules in place in the US for example, the point of diminishing returns happens fairly fast.
As we weâve discussed - we have 5Ghz 4500 (425 and 400c) links installed with impressive results, but nothing I can add for 6Ghz. However, the performance should be very similar in any installation with similar channel widths and similar RSSI/SNR.
So Jacob - we have no 4600 stuff - but I understand this to mean that even on PTP links, the AFC is still necessary in 6Ghz gear, right? Youâre saying thereâs no âFixed PTP Linkâ exception to the AFC then, right?
The radios used for PtP 6GHz/AFC use cannot be registered as licensed PtP links with the FCC. Due to AFC rules youâre limited to upto 36dBm EIRP on both sides of the link. In addition, the farther the link is, the more likely that the AFC will reduce the allowed EIRP and/or restrict channels being used due to incumbent licensed 6GHz operators. Another issue is that the far side will start up in standard âlowâ power mode at 5dBm TX power⌠which at farther distances, might not be enough power to form a link, and if it canât form a link, then it canât download its AFC table to make the transition to fixed âhighâ power mode.
All of the above mentioned items should be of concern to those operators that want to use 6GHz/AFC for long distance links.
1 Like
This. Eric nailed it.
Thank you for the insight/info provided. If there are no incumbent 6ghz in the area of the further link the AFC should allow said radios to run at the full 36dBm correct? As per the cambium AFC tool all is clear but could the tool report wrong and one is left with a surprise? As for the far side, there is no way to have it power up in a different mode?
When the radio boots it will be in standard power mode until it can contact the AFC to get clearance for the additional 6dBm of TX power.
2 Likes
One thing I just thought of⌠if this is a backup link, and if both ends of the 6GHz/AFC link can reach the internet, then they might be able to transition from standard to fixed without having to be connected first. I have not tested this configuration however.
That is brilliant, thank you, I am going to try that. I will report my findings once equipment arrives and we can deploy it.
I donât really see the radios starting up in standard/low power power mode being a real problem for longer PtP links. If I remember correctly, standard power is 30dBm EIRP, and if youâre within 6dB of the link not being functional, you really donât want to be using these radios on that link anyway.
The longest PtP 6ghz link Iâve tried so far is only 3.5 miles using a pair of Force 4625âs⌠it will be interesting to see what can be done with 4600câs on 2 or 3 foot dishes.
I guess I should have defined âlongâ distance PtP links⌠I meant over 5 miles. Try out some larger dishes and distances and let us know how it goes!
Right, Iâm thinking that over 5 miles should easily be doable. If Iâm targeting a minimum signal level of around -70 for a useful link, that means it will only drop to about -76 in low power mode, which should be plenty for it to get connected to the AFC (as long as we arenât dealing with high noise levels). With 2â dishes, we should theoretically be able to that kind of signal levels up to somewhere around 7 miles.
Thanks for your insights Eric. We have 4500 gear, but we have no 4600 gear â but I do have another question. On the 4600c (which say they have a GPS puck) if two 4600câs are used for a PTP link, does the AP/Master side use that GPS for GPS Sync Timing (in a TDD PTP mode?) In other words, can I sync a number of 4600c backhauls, if I have several APâs on the same tower?
Timing/sync and tdd ratio is set by the AP/master.
Yes, of course. 
I was asking if the 4600c SMâs (or 4625 SMâs for that matter) GPS was active in TDD AP/Master mode.
Hmmm⌠from what Iâm seeing it doesnât appears as though sync is even possible with the F4600c or F4625 in AP/master mode, even with GPS enabled. GPS appears to only be used for the AFC. The area of the GUI with Synchronization settings is not available. You will need to use the F4600L as an AP/master in order to use sync. The spec sheets confirm this.
Ok, thanks Eric. Dang, thatâs too bad. But thanks, you saved me buying a bunch with incorrect expectations.
Maybe a bit late answer, but we managed to get 1.2Gbps bandwidth at 40 kilometers with 4600C. We used 3 feet antenna
2 Likes