Using a cron job to test my broadband speed every 30 mins from
http://www.thinkbroadband.com/speedtest.html I see that my broadband speed didn't drop below 12Mb/s on Saturday
09/03/10 23:30:01 1.41 MB/s 20971520/20971520
09/04/10 00:00:00 2.15 MB/s 20971520/20971520
09/04/10 00:30:00 1.69 MB/s 20971520/20971520
09/04/10 01:00:00 2.20 MB/s 20971520/20971520
09/04/10 01:30:01 1.70 MB/s 20971520/20971520
09/04/10 02:00:00 2.22 MB/s 20971520/20971520
09/04/10 02:30:00 1.88 MB/s 20971520/20971520
09/04/10 03:00:00 2.22 MB/s 20971520/20971520
09/04/10 03:30:01 2.04 MB/s 20971520/20971520
09/04/10 04:00:00 2.17 MB/s 20971520/20971520
09/04/10 04:30:00 1.45 MB/s 20971520/20971520
09/04/10 05:00:01 2.19 MB/s 20971520/20971520
09/04/10 05:30:00 2.01 MB/s 20971520/20971520
09/04/10 06:00:00 1.98 MB/s 20971520/20971520
09/04/10 06:30:00 1.67 MB/s 20971520/20971520
09/04/10 07:00:01 2.22 MB/s 20971520/20971520
09/04/10 07:30:00 1.95 MB/s 20971520/20971520
09/04/10 08:00:00 2.12 MB/s 20971520/20971520
09/04/10 08:30:00 1.67 MB/s 20971520/20971520
09/04/10 09:00:00 2.22 MB/s 20971520/20971520
09/04/10 09:30:01 1.52 MB/s 20971520/20971520
09/04/10 10:00:00 1.88 MB/s 20971520/20971520
09/04/10 10:30:00 1.24 MB/s 20971520/20971520
09/04/10 11:00:00 1.51 MB/s 20971520/20971520
09/04/10 11:30:00 1.24 MB/s 20971520/20971520
09/04/10 12:00:00 2.11 MB/s 20971520/20971520
09/04/10 12:30:00 1.80 MB/s 20971520/20971520
09/04/10 13:00:00 1.98 MB/s 20971520/20971520
09/04/10 13:30:01 1.66 MB/s 20971520/20971520
09/04/10 14:00:00 2.01 MB/s 20971520/20971520
09/04/10 14:30:00 1.56 MB/s 20971520/20971520
09/04/10 15:00:00 1.94 MB/s 20971520/20971520
09/04/10 15:30:01 1.85 MB/s 20971520/20971520
09/04/10 16:00:01 2.15 MB/s 20971520/20971520
09/04/10 16:30:00 1.52 MB/s 20971520/20971520
09/04/10 17:00:00 2.16 MB/s 20971520/20971520
09/04/10 17:30:01 1.32 MB/s 20971520/20971520
09/04/10 18:00:00 1.68 MB/s 20971520/20971520
09/04/10 18:30:00 1.44 MB/s 20971520/20971520
09/04/10 19:00:00 2.14 MB/s 20971520/20971520
09/04/10 19:30:01 1.37 MB/s 20971520/20971520
09/04/10 20:00:01 2.17 MB/s 20971520/20971520
09/04/10 20:30:00 1.74 MB/s 20971520/20971520
09/04/10 21:00:00 2.05 MB/s 20971520/20971520
09/04/10 21:30:00 1.69 MB/s 20971520/20971520
09/04/10 22:00:01 2.17 MB/s 20971520/20971520
09/04/10 22:30:00 1.83 MB/s 20971520/20971520
09/04/10 23:00:00 2.18 MB/s 20971520/20971520
09/04/10 23:30:00 1.88 MB/s 20971520/20971520
09/05/10 00:00:00 2.14 MB/s 20971520/20971520
NB: speeds listed in megabytes not megabits. Assuming a couple of stop bits with every byte then I guess you need to multiply by 10 to convert.