If you get plenty of sunshine in your area, then you can check/calculate the prayer times on your own and then see which of them is more accurate.
For Fajr, look for bright horizontal light coming from the East. That is known as the true dawn.
For Ishraq, keep looking for sunrise. As soon as you see the upper tip of the sun, Fajr time ends. Then wait for the sun to rise completely until it is almost 1.5-2 meters high. It takes approximately 15-20 minutes from Sunrise. That is the time for Ishraq.
For Zuhr, wait for the sun to reach its peak. Then 5 minutes later when it starts going down, Zuhr time starts. You can plant a stick in the ground to check the shadow. Before Zuhr, the shadow will fall on west side of the stick. As soon as it starts falling towards the east side, Zuhr time starts.
Also, measure the shadow length when the sun is at its peak, ie when the shadow is exactly in the center, neither towards east, nor towards west. You will need this measurement while calculating Asr time.
Now for Asr, wait for the shadow to become equal in length as that of the stick + the shadow measurement you did above at the sun's peak. This will be the start of Asr time.
(According to Hanafi madhhab, wait for the shadow to be twice that of the object height instead of being equal)
The Asr time will end when the sun becomes yellow at the time of sunset.
When the sun sets completely, Maghrib time will start.
Maghrib time is until the sky is reddish brown. When it becomes black, Isha time starts.
Please see this link for more details:
http://www.moonsighting.com/how-we.html