Isn't a higher sync speed than 7616Kbps possible with interleaving?
yes, provided both ends support S=1/2 or something with a similar name
8128 sync interleaved here at >35 dB signal attenuation
It was a TG585 v7:
Vendor ID (Local/Remote): TMMB / P
TMMB = Thomson MultiMedia Broadband / P = ?